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Glossary

Glossary

Jewellery Glossary: Diamond, Gemstone and Ring Terms Explained

Plain-English definitions of the 1129 terms used across our education guides.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

A-centre

A nitrogen defect in diamond where nitrogen atoms occur in pairs. A-centres are common in natural diamonds and typically have little visible effect on colour.

ABN

Australian Business Number, an 11-digit identifier for businesses in Australia. Shoppers can check a jeweller's ABN on the Australian Business Register to confirm it is a registered business.

Abrasion

Surface wear on a gemstone or metal caused by rubbing or scratching. It appears as tiny scratches or dulled facet edges, especially on softer materials.

Acute corner

A sharp, narrow-angled point on a fancy-cut stone, such as a marquise tip or pear point. These corners are prone to chipping and are usually protected by a prong or V-tip.

Read more: Lapis Lazuli

Agreed value

An insurance arrangement where the insurer and owner settle on the value of an item, such as a ring, when the policy begins. That amount is paid out if the item is lost or destroyed.

Akoya pearl

A cultured saltwater pearl grown in Akoya oysters, mainly in Japan and China. Akoyas are known for their round shape, high lustre and typically white or cream colour with rosé overtones.

Read more: Rhodolite Garnet

Ametrine

A natural quartz that shows both purple amethyst and golden-yellow citrine colours in a single stone. Most ametrine comes from Bolivia.

B

B-centre

A nitrogen defect in diamond where four nitrogen atoms surround a vacancy. It is found in some natural diamonds and does not strongly affect colour.

Baguette

A small, narrow rectangular step-cut gemstone. Baguettes are often used as side stones to flank a larger centre stone.

Bail

The small loop or fitting on a pendant that lets a chain or cord pass through it.

Band depth

The thickness of a ring band measured from the inside to the outside of the ring, affecting how heavy and sturdy it feels.

Read more: Bracelet Size Guide

Bar setting

A setting where stones are held between thin metal bars, so the sides of the stones are open to light. It is also called a channel-style or tension-like look when stones sit side by side.

Read more: Sandblasted Ring Finish

Bead nucleus

The small round bead, typically polished freshwater mussel shell, inserted into an oyster to start a cultured pearl. Nacre then builds up around it.

Bead setting

A way of securing a stone by raising small beads of metal from the surrounding surface and pressing them over the stone's edge. Also called grain setting.

Bead-nucleated

Describes a cultured pearl grown around a round bead, usually shell, placed in the oyster. The oyster coats the bead with layers of nacre. Most round saltwater cultured pearls are made this way.

Read more: Types of Necklace Chains

Belly

The curved lower part of a gemstone's pavilion, or a bulge in a ring shank or setting. In stones, an excessively rounded pavilion can make a stone look smaller.

Beryl

A mineral family of beryllium aluminium silicate that includes emerald, aquamarine, morganite and heliodor. Pure beryl is colourless, and trace elements create the different colours.

Beryllium diffusion

A treatment where sapphires or rubies are heated with beryllium so that colour penetrates the stone. It can change or deepen colour, and sellers should disclose it.

Bezel

A metal rim that wraps around the edge of a gemstone to hold it in place. It gives a smooth, secure hold with no prongs to snag.

Bezel (face)

On a faceted gemstone, one of the larger kite-shaped facets on the crown that sit between the table and the girdle. Also called a main or star-bezel facet in some cut diagrams.

Read more: Mokume Gane Rings Melbourne

Binder

A material used to hold powders or fragments together. In jewellery it may mean a resin or glue in composite stones, or a binding agent in metal clay.

Read more: Types of Necklace Chains

Boron

A trace element that gives natural blue diamonds their colour. Diamonds containing boron are classed as type IIb and can conduct electricity.

Boulder matrix opal

Australian opal from Queensland where the precious opal is found throughout the ironstone host rock, forming a speckled or patchy pattern of colour within the dark stone.

Read more: Sandblasted Ring Finish

Brushed finish

A metal surface finish made with fine abrasive brushing, leaving soft parallel lines. It looks matte and satin-like and hides small scratches well.

Bruted girdle

A diamond girdle left with a frosted, slightly rough finish from the bruting process, rather than being polished smooth or faceted.

Bruting

The process of shaping a diamond's girdle by rubbing two diamonds against each other, usually on a lathe, to make the stone round before final polishing.

Bullet back

A simple earring back shaped like a small bullet, with a push-on fitting that grips the post. It is also called a friction back and is easy to use.

Burn mark

A cloudy or whitish surface mark on a gemstone caused by heat during polishing or cutting. It can usually be removed by repolishing.

Burnishing

A technique of rubbing a smooth, hard tool over metal to polish it or to press metal over a stone's edge, as is done in bezel and flush settings.

Burnout

A step in lost-wax casting where a mould holding a wax model is heated until the wax melts and burns away, leaving a cavity for molten metal.

Butterfly back

A common earring back, also called a scroll back, with two small wings that you squeeze to slide onto the post. It holds the earring firmly against the ear.

Read more: Earring Back Types

Buying shy

When a shopper hesitates to commit to a purchase, often from worry about price or quality. In jewellery, it may also mean buyers avoiding a stone or style they perceive as risky.

C

C-axis

The main optical axis in some crystals, such as quartz, corundum and beryl. Light behaves differently along this direction, which affects colour and how stones are cut.

Cable (trace) chain

A classic chain made of evenly sized oval links connected one to the next, alternating direction. It is simple, strong and popular for pendants.

Read more: Types of Necklace Chains

Cabochon

A gemstone shaped and polished into a smooth, domed form without facets. Opals, turquoise and moonstone are commonly cut this way.

CAD

Computer-aided design: software used to create precise 3D models of jewellery before it is made. It lets designers and customers review a piece before casting or setting.

CAD (computer-aided design)

Software used to build detailed 3D digital models of jewellery before production. It allows changes to be made and approved before the piece is cast or crafted.

CAD render

A realistic image produced from a 3D computer model of a jewellery design. It shows how the finished piece should look before it is made.

Cairngorm

A smoky yellow-brown to grey-brown variety of quartz, named after the Cairngorm mountains in Scotland. It is traditionally used in Scottish jewellery.

Read more: Lapis Lazuli

Calibrated

Describes gemstones cut to standard sizes so they fit ready-made settings. This makes stones interchangeable and helps matching in a design.

Read more: Diamond Cavities and Chips

Cedarwood oil

An oil traditionally used to improve the appearance of emeralds and other fractured stones by filling surface-reaching cracks. It is a common, accepted treatment.

Centipede inclusion

A feature in some gemstones, notably Mogok-style spinel and sapphire, that looks like a tiny, many-legged centipede. Most often seen in natural stones, it can help identify origin.

Read more: Diamond Cavities and Chips

Choker

A necklace that fits closely around the neck, typically 30 to 41 cm long. Chokers can be made from chain, beads, ribbon or solid metal.

Read more: Necklace Length Guide

Chromium

A trace element that gives emeralds their green colour and rubies their red. It is the main colouring agent in several well-known gemstones.

Chrysoberyl

A hard gemstone, rated 8.5 on the Mohs scale, found in yellow-green and golden colours. Varieties include alexandrite, which changes colour, and cat's eye.

Chunky facets

Large, broad facets on a gemstone that give a bold, less sparkly look than many small facets. They suit statement pieces and darker or included stones.

Read more: Graining in Diamonds

Clarity enhancement

A treatment that makes a gem's internal flaws less visible, such as laser drilling or filling fractures with glass or resin. It should be disclosed, as it can affect value and durability.

Clarity grade

A rating of how free a gem is from internal inclusions and surface blemishes. For diamonds, the scale runs from Flawless to Included (I3).

Clarity plot

A diagram on a diamond grading report that maps the type and position of the stone's inclusions and blemishes. It helps identify the stone and shows where flaws sit.

Clarity treatment

Any process used to improve a gem's apparent clarity, such as laser drilling, fracture filling or heating. Treated stones are usually worth less than untreated ones and should be disclosed.

Clarity type

A classification of how many inclusions a gemstone type typically has. Type I stones are usually clean, Type II often have some, and Type III are almost always heavily included, such as emerald.

Claw

A small metal arm that grips a gemstone to hold it in a ring or other jewellery. Also called a prong.

Claw (prong)

A small metal arm that holds a gemstone in place in a setting. Claw and prong mean the same thing; claw is the common Australian term.

Claw head

The part of a ring or pendant that holds the stone with several claws. It is usually a separate piece that sits above the band or chain.

Read more: Amber

Copper-bearing tourmaline

Tourmaline coloured by copper, producing vivid neon blues and greens, such as Paraíba-type stones. These are rare and highly valued.

Read more: Bracelet Size Guide

Cubic zirconia

A lab-created zirconium dioxide crystal, usually colourless, widely used as an inexpensive diamond simulant. It is heavier than diamond and scratches more easily.

Culet

The small facet, or sometimes just a point, at the bottom tip of a faceted gem's pavilion. It helps protect the tip from chipping.

Cultured pearl

A real pearl formed in a mollusc after people place a nucleus or tissue inside it. The pearl is made naturally by the animal but with human intervention.

Read more: Types of Necklace Chains

Curved (contour) band

A ring band shaped with a curve or notch so it sits closely against an engagement ring or another band, leaving no gap between them.

Curved (convex) trilliant

A triangular gem cut whose three sides bow outwards in a gentle curve, rather than being straight. It gives a softer shape than a standard trilliant.

D

D-shape

A ring band profile that is flat on the inside and domed outside, resembling the letter D on its side. It is sometimes called a half-round band.

D-shape profile

A ring band cross-section that is rounded on the outside and flat on the inside, like a letter D. It is comfortable to wear and has a classic look.

Darkfield illumination

A microscope lighting method in which light reaches the gem from the sides against a dark background. It makes inclusions and internal features easier to see.

Darkfield lighting

A gemmological microscope setting that lights a stone against a dark background, so inclusions stand out as bright features and flaws are easier to see.

Read more: Mokume Gane Rings Melbourne

Density

The mass of a material for a given volume. Gemmologists compare it with specific gravity to help identify gemstones, as each gem has a typical value.

Depth percentage

A gem's total height from table to culet divided by its average width, shown as a percentage. It is a key measure of how well proportioned a cut stone is.

Diameter

The width of a round gem or ring measured straight across its centre. For round diamonds it is usually given in millimetres, and for rings it indicates the inner size.

Diamond Dossier

A shorter diamond report from GIA for stones under one carat. It gives the main grades and measurements but has no plotted clarity diagram.

Diamond equivalent weight

The weight a diamond would have if it matched the size of a diamond simulant or other gem. Retailers use it to compare simulant sizes with real diamond carat weights.

Diamond equivalent weight (DEW)

The carat weight of a diamond with the same dimensions as a different stone, such as moissanite. It helps shoppers compare how large the stones look.

Diamond grading report

A document from a gemmological lab that records a diamond's measurements and grades for the 4Cs, with a diagram of clarity features. It does not state a dollar value.

Diamond origin report

A lab document that aims to identify where a diamond came from, such as its country of mining or whether it was lab grown. Methods and reliability vary.

Diamond simulant

A material that looks like diamond but has a different chemistry or structure, such as cubic zirconia or moissanite. It is not real diamond.

Diamond type

A scientific classification of diamonds by nitrogen and boron content, such as Type Ia or Type IIa. It helps labs identify treatments and distinguish natural from lab-grown stones.

DiamondView

A lab instrument that uses strong ultraviolet light to show a diamond's growth patterns. It helps tell natural diamonds from lab-grown ones.

Dichroism

A gem's property of showing two different colours when viewed from different directions. It is seen in doubly refractive stones and helps with identification.

Die-struck

A way of making metal jewellery by pressing a sheet of metal between steel dies to stamp a precise shape or design. It suits consistent, mass-produced pieces.

Diffusion

A treatment in which elements are heated into a gem's surface to change its colour, such as in some sapphires. The colour may sit only near the surface.

Diffusion bonding

A joining method where metal parts are pressed together under heat so their atoms intermingle, forming a solid bond without solder or melting. It is used in some precision jewellery and layered metal work.

Read more: Mokume Gane Rings Melbourne

Diffusion treatment

A heat treatment that introduces colour-causing elements, such as beryllium in sapphire, into a gemstone's surface or body. The colour may be shallow and should be disclosed at sale.

Digging out

A cutting flaw where a stone's pavilion or facets are cut too deep or uneven, creating a dark or dull area. It can also mean removing a stone from its setting.

Directionality

The way a gemstone's appearance or property, such as colour, hardness or sparkle, changes depending on the direction it is viewed or cut. It also describes the orientation of patterns in some stones.

Read more: Zircon

Double rose cut

A cut with a rose-style faceted dome on both the top and bottom of the stone, with no flat table. It is seen in some antique and vintage-inspired jewellery.

E

Eagle claw

A prong style with pointed or tapered tips that curve over a gemstone, resembling a bird's talons. It holds the stone securely and suits larger or more angular cuts.

East-west setting

A setting where an elongated stone, such as an oval, emerald or marquise cut, sits horizontally across the finger rather than along it. It gives a modern, wider look.

Elbaite

The tourmaline species that produces most gem-quality colours, including pink, green, blue and multicoloured stones. Watermelon and Paraíba tourmalines are varieties of elbaite.

Electroplating

A process that uses an electric current to coat an item with a thin layer of metal, such as gold, rhodium or silver. The coating can wear away over time.

Elongated cushion

A rectangular cushion-shaped cut with rounded corners and softly curved sides. Its length is noticeably greater than its width.

Read more: Necklace Length Guide

Extender chain

A short length of chain attached to a necklace or bracelet clasp so the wearer can lengthen it. It also allows adjustable wear at different lengths.

Read more: Bracelet Size Guide

Extinction

Dark areas seen in a gemstone when it fails to return light to the viewer's eye, due to the way light passes through it. In gemmology, it also describes darkness under crossed polarising filters.

Extra facet

An additional small facet outside a diamond's standard cut pattern, often placed to remove an inclusion or retain weight. It can slightly affect symmetry grading.

Eye-clean

A gemstone with no inclusions visible to the unaided eye when viewed normally from a typical distance. Small flaws may still be seen under magnification.

F

Face-down colour

The colour of a loose diamond as seen with the stone upside down, table down, which is how colour is graded. It is usually judged against master stones in controlled lighting.

Face-down grading

The practice of assessing a diamond's colour with the stone placed table-down, allowing the body colour to be compared consistently. It reduces the influence of the top facets' sparkle.

Read more: Earring Back Types

Fine silver

Silver that is 99.9% pure, marked 999. It is soft and bright white, so it is used less often for everyday jewellery than sterling silver.

Read more: Bracelet Size Guide

Fitted (contour) band

A wedding band curved to follow the shape of an engagement ring's setting, so the two rings sit flush together.

Fitted (contoured) band

A wedding band with a curved or shaped edge made to fit around an engagement ring and sit neatly beside it.

Fitted (shadow) band

A narrow, often diamond-set band shaped to nestle against an engagement ring, adding a matching 'shadow' of sparkle.

Fitted band

A wedding band shaped, often with a curve or notch, to sit snugly against an engagement ring without a gap.

Fitted wedding band

A wedding ring made with a curve or notch so that it sits closely against a particular engagement ring.

Fixed back

An earring or pendant back that is permanently attached or does not move, rather than a removable or adjustable one.

Fixed station

A bead, stone or charm permanently fixed at a set point on a chain or cord, so it doesn't slide along.

Flame fusion (Verneuil)

The first commercial synthetic gem process, developed by Auguste Verneuil. Powder is melted in a flame and falls to form a crystal boule.

Flame-fusion

A method of making synthetic gems by melting powder in an oxy-hydrogen flame so it crystallises. It is used for lab-grown rubies, sapphires and spinel.

Flanders cut

A square diamond cut with a modified brilliant facet pattern, patented in 1988 by Basil Watermeyer. It has 61 facets and a distinctive look.

Read more: Earring Back Types

Flat court

A wedding band profile that is flat on the outside and rounded inside for comfort, giving a modern look.

Flawless (FL)

The top diamond clarity grade, meaning no inclusions or blemishes visible under 10x magnification by a trained grader. Flawless diamonds are extremely rare.

Read more: Tennis Necklaces Explained

Four-claw setting

A stone setting held by four metal claws, giving a clear view of the gem. It shows more of the stone but offers less security than six claws.

G

Gallery

The area under the stone in a ring setting, between the head and the shank. It is often decorated with open metalwork or pierced designs.

Gallery rail

A horizontal strip of metal in a ring's gallery that links the prongs or supports under the stone, adding strength and decoration.

Read more: Rhodolite Garnet

Gauge

A measure of the thickness of wire, sheet metal or earring posts. Gauge numbers run in reverse, so a higher number means thinner metal.

Read more: Earring Back Types

Geometric cut

A gemstone cut with straight-edged shapes and symmetrical facets, such as square, rectangle, triangle or hexagon, rather than rounded outlines.

Read more: Tennis Necklaces Explained

Grain setting

A setting method where small beads of metal are raised from the surrounding surface to hold a stone. It is also called bead setting.

Graining

The process of raising tiny beads of metal with a tool to secure a stone in a setting, or a texture on metal that looks like fine grains.

Graphite

A soft, grey-black form of carbon with a layered structure. It is the same element as diamond but with very different properties.

Graphitisation

The conversion of diamond into graphite at very high temperatures without oxygen. It can make a diamond's surface dark or cloudy if overheated.

Graver

A steel hand tool with a sharp point, used to cut lines in metal for engraving, stone setting and carving details.

Greenwashing

Misleading or exaggerated claims that a product or business is environmentally friendly or ethical. In Australia such claims can breach consumer law.

Grid emission intensity

The amount of greenhouse gas emitted per unit of electricity from a power grid. It affects the carbon footprint of processes such as lab-grown diamond production.

Grit

The size of abrasive particles in sandpaper, polishing compounds or diamond tools. Lower numbers are coarser and higher numbers are finer.

Grossular

A calcium aluminium garnet species found in many colours. Its varieties include green tsavorite and orange-brown hessonite.

Growth sector

A zone within a crystal that formed in a particular direction as it grew. In diamonds, different sectors can vary in colour or in how they take up impurities.

Growth striations

Fine parallel lines or bands inside or on a gemstone that show how the crystal grew. They can help identify a stone, for example natural versus synthetic.

GST

Goods and Services Tax, a 10 per cent tax added to most goods and services sold in Australia, including jewellery.

GST-free export

A sale of goods sent outside Australia, which can be exempt from GST if export conditions are met. Tourists may claim refunds under separate schemes.

Gypsy setting

A setting where a stone sits flush in a hole drilled into the metal, with the surrounding metal pressed over the edge. It is also called a flush setting.

H

Half eternity

A ring style with gemstones set across the top half or so of the band, with the rest plain metal. It is easier to resize than a full eternity ring.

Half moon

A semicircular gemstone shape, with one straight edge and one curved edge. It is often used as a side stone beside a centre stone.

I

Ideal 0

A term for a very high standard of diamond cut, often meaning the best cut grade with excellent polish and symmetry.

Idealscope

A viewing tool that shows how a diamond handles light, using colour-coded patterns to reveal light leakage and cut quality.

Idiochromatic

Describes a gemstone whose colour comes from an element that is part of its basic chemistry, such as malachite's copper or peridot's iron.

Illusion setting

A setting with a reflective metal plate around the stone so it looks larger than its true size.

Imperial topaz

A rare, high-quality topaz with golden-orange to pinkish-orange colour, prized above other topaz varieties.

J

Jadeite

One of two minerals called jade, prized for its intense colours, especially rich emerald green. It is rarer and usually more valuable than nephrite.

Read more: Jade

Jardin

A French term for the inclusions in an emerald, meaning garden. These mossy internal features are common and are accepted as part of emerald's natural character.

Jeweller's rouge

A fine iron oxide polishing compound, usually red, used to give gold and other metals a high shine. It is typically applied on a buff or cloth.

K

Keel

On a cut gemstone, a ridge along the bottom where pavilion facets meet, as in a long keel-shaped base. It can also describe the underside's ridge line.

Keel line

The line or ridge at the base of a gemstone's pavilion where the main facets meet. Some stones, like certain fancy cuts, have an elongated keel instead of a point.

Keeper ring

A plain band worn next to another ring, such as an engagement ring, to hold it in place or keep it from spinning or slipping.

Keshi

A small, irregular pearl formed without a nucleus, usually as a by-product of pearl culturing. Keshi pearls are solid nacre and valued for their lustre and unique shapes.

Keshi pearl

A small, non-nucleated pearl formed accidentally in cultured pearl oysters. Made entirely of nacre, keshi pearls are often irregular in shape and have strong lustre.

Key to symbols

The legend on a diamond grading report explaining the symbols on the clarity plot. It shows what each mark means, such as crystals, feathers or clouds.

Kimberley Process

An international initiative that aims to stop conflict diamonds entering the legitimate market. Participating countries certify rough diamond shipments as conflict-free.

Kimberley Process Certification Scheme

The system of government-issued certificates that accompany rough diamond shipments. It aims to ensure the diamonds have not funded rebel conflicts.

Kimberlite

A volcanic rock that forms vertical pipes and is the main primary source of diamonds. It is named after Kimberley, South Africa.

Kite cut

A gemstone cut with a four-sided kite outline, with two long and two short adjacent sides. It is a fancy shape used for accent stones or distinctive centre stones.

L

LA-ICP-MS

Laser ablation inductively coupled plasma mass spectrometry, a lab method that vaporises a tiny sample to measure trace elements. Gemmologists use it to help determine a gem's origin or treatment.

Lab-created

Made in a laboratory rather than mined from the earth. Lab-created gems have the same chemical composition as natural counterparts or are synthetic versions of them.

Lab-created emerald

An emerald grown in a laboratory, with the same chemistry and crystal structure as natural emerald. It typically has fewer inclusions and costs less.

Lab-created gemstone

A gemstone produced in a laboratory with the same chemistry, crystal structure and properties as its natural counterpart. It must be disclosed as lab-created when sold.

Lab-created sapphire

A sapphire grown in a laboratory from corundum, with the same chemistry and hardness as natural sapphire. It is usually cheaper and often cleaner.

Lab-grown diamond

A real diamond produced in a laboratory using high pressure or vapour deposition. It has the same chemistry and structure as mined diamond, and should be disclosed as lab-grown.

Laboratory-grown diamond

A diamond made in a laboratory with the same crystal structure and properties as a mined diamond. It is produced by HPHT or CVD methods and graded in the same way.

Labradorescence

A play of iridescent colour, often blue or green, seen as a gemstone is turned. It is caused by light interference in layers within labradorite.

Read more: Labradorite

Lamproite

A rare volcanic rock that can carry diamonds, like kimberlite. Western Australia's Argyle mine was a famous lamproite source.

Landed cost

The total cost of an imported item delivered to the buyer, including price, shipping, insurance, duties and taxes such as GST.

Lariat

A long necklace without a clasp, worn looped or with one end threaded through the other. It often ends in tassels, beads or drops.

Read more: Necklace Length Guide

Laser drill hole

A tiny channel made by a laser to reach an inclusion inside a diamond, so it can be bleached or removed. It may be visible under magnification.

Laser drilling

A diamond treatment using a laser to bore a tiny tunnel to a dark inclusion. Acid then lightens or removes it, improving apparent clarity.

Laser engraving

Marking a design or text onto metal or other surfaces using a laser. It allows precise, detailed personalisation of jewellery.

Laser inscription

A tiny identifying mark, such as a report number, engraved on a diamond's girdle by laser. It is usually only visible under magnification.

Laser welder

A machine that joins or repairs metal using a focused laser beam. Jewellers use it for precise work with little heat spread to nearby stones.

Laser welding

Joining or repairing metal with a tightly focused laser. It allows precise repairs close to heat-sensitive gemstones.

Latch back

An earring fastening where a hinged latch closes over the post or wire to hold it in place. It is secure and often used on drop earrings.

Laterite

A reddish, iron- and aluminium-rich soil or rock formed by tropical weathering. It can host deposits of some gemstones and minerals, including nickel and bauxite.

Lattice diffusion

A treatment where heat drives colouring elements, such as titanium or beryllium, into a gemstone's crystal structure. It is commonly used on sapphires.

Lazurite

The deep blue mineral that gives lapis lazuli its colour. It is usually mixed with other minerals such as calcite and pyrite.

Read more: Lapis Lazuli

Lead time

The time between placing an order and receiving the finished item. For made-to-order jewellery it covers design, casting, setting and finishing.

Read more: Mokume Gane Rings Melbourne

Lipophilic

Oil-loving: describes a substance that bonds readily with oils and greases. In gemmology, it explains why some stones attract grease and why oil-based treatments adhere to them.

Liquid inclusion

A pocket of liquid trapped inside a gemstone as it formed. It may also hold a gas bubble or small crystal, and it helps identify natural stones.

Liver of sulphur

A sulphur-based chemical used to darken silver and copper, giving an antique look. It is applied to make recessed detail stand out.

Read more: Earring Back Types

Long base

A ring setting or band with an elongated base. It is usually used for a long gemstone or design, such as a baguette or marquise, sitting along the finger.

M

Mabe

A cultured pearl grown against the inside of an oyster shell rather than within the oyster's body. It has a flat back and a domed, lustrous front, and it is usually set in rings and earrings.

Read more: Necklace Length Guide

Matrix

The host rock in which a gemstone forms or is found. In opals and turquoise, the matrix can remain visible in the finished stone.

Read more: December Birthstone, Turquoise

Matte finish

A non-reflective, soft-looking surface on metal, made by brushing, sandblasting or etching. It gives a subtle look and hides small scratches.

Read more: Sandblasted Ring Finish

Media

The materials used in polishing, tumbling or cleaning jewellery, such as abrasive grit, steel shot or ceramic beads.

Read more: Sandblasted Ring Finish

Melee

Small diamonds, usually under 0.20 carats, often used as accent stones or in pavé. They are normally sold in groups rather than individually.

Melt value

The worth of a piece of jewellery based only on its precious metal content if melted down. It ignores design, gemstones and craftsmanship.

Metallic flux inclusion

A tiny flaw in synthetic gems grown by flux methods, where metal or leftover flux is trapped inside. It can help identify lab-grown stones.

Metamict

A gem mineral whose crystal structure has been damaged by natural radiation. Zircon is a common example, and its properties can change.

Read more: Zircon

Metastable

Stable under normal conditions but not truly so in the long term. Some materials, such as certain amber or treated stones, can change over time.

Micro-pavé

A fine form of pavé where very small diamonds are set closely together using tiny beads of metal. It creates a smooth, sparkling surface.

Microcrystalline quartz

Quartz made of crystals too small to see without magnification. Agate, jasper and chalcedony are examples.

Micron

A unit of length equal to one-thousandth of a millimetre. It is used to measure very thin layers such as gold plating.

Milgrain

A decorative edge of tiny beads of metal, often found on vintage-style rings and settings. It adds fine detail and an antique look.

Milgrain tool

A hand tool with a serrated edge, used to press a row of tiny beads along the edge of metal. It creates milgrain detail.

Milk and honey effect

A optical effect in some gemstones, such as cat's-eye chrysoberyl, where one side of the eye looks milky and the other honey-coloured when lit from the side.

N

N3 centre

A defect in diamond formed by three nitrogen atoms around a vacancy. It causes blue fluorescence and a faint yellowish tint in 'Cape' diamonds.

Nacre

The iridescent material secreted by molluscs, made of microscopic aragonite layers. It forms pearls and mother-of-pearl and gives them their lustre.

Nailhead

A small, plain, rounded or flat-topped metal stud set into jewellery for decoration. It can also describe a gem setting resembling a nail's head.

Native cut

A traditional gem cut, often rough and uneven, made in the country of origin to retain as much weight as possible rather than maximise sparkle.

Natural

A gem formed by nature without human creation, though it may be cut, polished or treated. Sellers should clearly say if a natural stone has been treated.

Natural (girdle)

A small area of a diamond's original rough surface left unpolished on the girdle. It is usually noted on grading reports and rarely affects appearance.

Natural (on the girdle)

A patch of original rough crystal surface left on a diamond's girdle. It is permitted if small and does not harm durability or beauty.

Natural diamond

A diamond formed deep in the earth over millions of years and mined, as opposed to a laboratory-grown diamond.

Read more: Jade

Nick

A tiny chip or notch on a gem's edge or facet junction, usually caused by knocks. It is generally a minor flaw.

Read more: Diamond Cavities and Chips

Nickel allergy

A skin reaction, such as redness and itching, caused by contact with nickel in some metal jewellery. Hypoallergenic or nickel-free metals help avoid it.

Nickel-white gold

White gold alloyed with nickel to give it its whitish colour. It is strong but can cause reactions in people with nickel allergy.

Nitrogen

The most common impurity in diamonds. Even small amounts can give a yellow or brownish tint and affect colour grade.

O

Obscuration

Something that blocks or dims light through a gem, such as heavy inclusions or a dark area, making part of the stone look cloudy or dark.

Obstruction

An inclusion or feature in a gem that blocks the passage of light, reducing brilliance or transparency.

Octahedral plane

A flat internal direction in a diamond's crystal structure, running parallel to octahedron faces. Diamonds can cleave along these planes, so cutters take them into account.

Off-centre culet

A cutting flaw where the pointed or flat bottom of a gem does not sit in the middle of the pavilion. It can reduce symmetry and brilliance.

Off-centre table

A cutting flaw where the large top facet of a gem is not centred on the crown. It reduces symmetry and may affect appearance.

Oiling

A common treatment where colourless oil or resin fills surface-reaching fractures in gems such as emerald, making them less visible. It should be disclosed.

Old European cut

An early round diamond cut with a small flat culet, high crown, deep pavilion and chunky facets. It was popular from the late 1800s to the early 1900s.

Old Mine cut

An antique cushion-shaped diamond cut from the 1700s to 1800s, with a high crown, small table, deep pavilion and large culet. It has a soft, candlelit sparkle.

Olivine

A mineral group, with magnesium-iron silicate as the main member. Its gem variety is peridot, a yellow-green stone.

Read more: Necklace Length Guide

Optical symmetry

The even, balanced arrangement of a gem's facets as seen through the top, affecting how evenly light returns. Good optical symmetry gives a sharper, more regular pattern of sparkle.

Organic gem

A gem formed by living organisms, such as pearl, coral, amber, jet or ivory. Organic gems are generally softer and more sensitive to chemicals, heat and knocks than mineral gems.

Read more: Amber

Orient

The soft, glowing iridescence seen on or just below the surface of a pearl, caused by light diffracting through its layered nacre. Strong orient is a mark of fine pearl quality.

Origin report

A gemmological laboratory document stating the likely geographic source of a gemstone, such as Kashmir, Burma or Colombia. It is based on testing of inclusions and trace elements.

OTL (over the limit)

A reading on a measuring instrument, such as a spectrometer or refractometer, that exceeds the upper range of the device. The value cannot be measured accurately and the test needs a different method.

P

Padparadscha

A rare sapphire with a delicate blend of pink and orange, often likened to a lotus blossom or sunset. Fine natural examples are highly valued.

Painting

Applying colour to a gem's surface or back, or to jewellery, to improve or change its appearance. In gem treatment, it is considered a disclosable enhancement.

Painting and digging

A traditional gem-cutting practice of marking a rough stone, then digging out sections to remove flaws before shaping. It helps reduce inclusions while retaining as much weight as possible.

Palladium white gold

A white gold alloy made with palladium rather than nickel to give its colour. It is naturally whitish, usually hypoallergenic and does not usually need rhodium plating.

Paper wear

Fine scratches or abrasion on a gem caused by rubbing against paper parcels or other stones in storage. It's usually minor and removed by re-polishing.

Read more: Zircon

Parti sapphire

A sapphire showing two or more distinct colours in one stone, such as blue, green and yellow zones. Cutters often orient it to display the colour contrast.

Parting

A break along a plane of weakness in a gem, caused by twinning or stress rather than natural cleavage. It looks like a flat, straight fracture.

Passenger concession

A customs allowance letting travellers bring a set value of goods into Australia duty-free. Jewellery can count toward the limit if it is not worn or in personal use.

Patch test

A skin test where a small sample of metal or material is held against the skin to check for allergic reaction. It's often used to detect nickel sensitivity.

Path length

The distance light travels through a gemstone. It affects how deep a colour appears, with longer paths producing stronger colour.

Patina

A soft surface change on metal that develops through age, wear or oxidation. Many people value it on antique pieces, though it can be polished away.

Pavilion

The lower part of a cut gemstone, from the girdle to the point at the bottom (the culet). Its angles control how light reflects back through the top.

Pavilion angle

The angle between the girdle plane and the main facets of the pavilion. It strongly influences a stone's brilliance and light return.

Pavilion main facet

One of the large, kite-shaped facets on the lower part of a brilliant-cut stone, extending from the girdle toward the culet. They reflect light back up through the crown.

Pavé

A style in which many small diamonds or gems are set closely together so the surface looks paved with stones. The metal is barely visible.

Pavé setting

A setting method in which small stones are held by tiny beads or claws close together across a surface. This creates a continuous sparkling effect.

Pd950

A hallmark meaning the item is 95 per cent pure palladium. It's a lightweight, naturally white metal often used as an alternative to platinum.

Read more: Labradorite

Planishing

Hammering metal with a smooth-faced hammer to smooth, harden and shape it. It leaves a distinctive faceted surface if left unpolished.

Read more: Graining in Diamonds

Plotting diagram

A schematic drawing on a grading report marking the position of a stone's clarity characteristics. It helps identify the stone and show where inclusions sit.

Point

A unit of diamond weight equal to one hundredth of a carat. For example, a 50-point diamond weighs 0.50 carats.

Point (carat)

One hundredth of a carat, or 2 milligrams. Jewellers use points to describe small diamonds, so a 25-point stone is a quarter of a carat.

Point (tip)

The sharp end of a claw, marquise or pear-shaped stone. Points are the most exposed part of a setting and are often protected with a V-claw.

Pointer

A small marker or tool used to indicate or locate a position. In gemmology, it can also mean a clue that helps identify a stone or its treatment.

Points

A unit of diamond weight, where one point equals one hundredth of a carat. A 50-point diamond weighs 0.50 carats.

Polariscope

A gemmological instrument using polarised light to show whether a stone is singly refractive, doubly refractive, or aggregate. It helps identify gems and detect strain.

Read more: Graining in Diamonds

Polish

The smoothness of a gem's facet surfaces after cutting. Good polish lets light enter and leave cleanly, while poor polish can leave marks or a hazy look.

Polish and symmetry

Two finish grades on a diamond report. Polish rates surface smoothness, while symmetry rates how accurately the facets are shaped and aligned.

Polish grade

A rating, usually from Excellent to Poor, of how smooth a gemstone's facets are. It appears on grading reports for diamonds.

Polish lines

Fine parallel scratches left on a facet during polishing. They are usually only visible under magnification and may lower the polish grade.

Polished rails

The smooth, shiny edges along the sides of a ring or bangle. They give a clean finished look and may be contrasted with a matt or textured centre.

Read more: Jade

Polymerisation

A chemical process where small molecules link into long chains to form a plastic or resin. In jewellery, it describes how resins harden, including those used in gem treatments.

Read more: Amber

Polysynthetic twinning

Repeated, thin, parallel twin layers within a crystal. It creates fine striations seen in feldspars such as labradorite and some corundum.

Read more: Labradorite

Porosity

The amount of tiny pores or spaces in a material. High porosity makes a gem more likely to absorb oils, dyes or chemicals.

Porous gemstone

A stone with tiny openings that can absorb liquids, such as pearls, opal, turquoise and coral. These need gentle cleaning and protection from chemicals.

Portable valuables cover

An insurance option that covers items like jewellery when you carry or wear them away from home. It may be listed as an extra to a home contents policy.

Post

The straight pin on an earring that passes through the ear and is held by a back. It can also mean a stem that holds a stone in a setting.

Read more: Earring Back Types

Post-growth treatment

Processing applied to a lab-grown diamond or gem after it has formed, such as heat or irradiation, to improve its colour or clarity.

Posy ring

A ring with a short verse or message engraved, traditionally on the inside of the band. The word comes from 'poesy', meaning poetry.

Potch

Opal without play of colour, often grey, white or milky. Australian miners use the word, and it can sit alongside precious opal in the same find.

Prasiolite

A pale green variety of quartz, usually made by heating amethyst or yellow quartz. It is sometimes sold as green amethyst.

Read more: Amber

Price per carat

The cost of a gemstone for each carat of weight. Total price is this figure multiplied by the stone's carat weight, and it rises steeply for larger, better stones.

Princess cut

A square or slightly rectangular brilliant cut with pointed corners and many facets. It is popular for engagement rings and needs protective claws on its corners.

Princess length

A necklace length of about 45 cm (18 inches). It typically rests at or just below the collarbone.

Read more: Necklace Length Guide

Product disclosure statement (PDS)

A document that explains an insurance policy's features, costs, limits and exclusions. Read it before buying jewellery insurance so you know what is covered.

Profile

The side view or shape of a ring, gemstone or band. It describes factors like height, curve and thickness, such as a D-shape or flat band.

Profile height

How far a ring or setting stands above the finger or surface. A high profile sits tall and is more exposed to knocks, while a low profile sits closer.

Promise ring

A ring given as a symbol of commitment, love or friendship. It is not a formal engagement or wedding ring.

Read more: Rhodolite Garnet

Pyralspite series

The garnet series that blends pyrope, almandine and spessartine. Because the members mix, many garnets sit between names and vary in colour and properties.

Read more: Lapis Lazuli

Pyroelectric

Describing a crystal that builds an electric charge when heated or cooled. Tourmaline is a well-known gem with this property, and it can attract dust.

Pyrope

A deep red garnet that is rich in magnesium. It is often clean and very hard-wearing, and is used in classic and antique jewellery.

Read more: Rhodolite Garnet

Q

Quality descriptor

A word or grade used to describe a gem or piece, such as 'Excellent' for cut or 'VS' for clarity. It gives a quick sense of quality, though grading scales differ between labs.

Quartz

A common, durable mineral made of silicon dioxide. Gem varieties include amethyst, citrine, rose quartz and smoky quartz.

Read more: Amethyst Jewellery, Amethyst, Ametrine

R

Radiant cut

A rectangular or square gemstone cut with trimmed corners and brilliant-style facets. It combines the outline of an emerald cut with extra sparkle.

Radiography

The use of X-rays to look inside a gem or pearl. It can show internal structure, such as the nucleus in a cultured pearl.

Read more: Lapis Lazuli

Recutting

Cutting and polishing a gem again to remove damage or improve its shape and sparkle. It reduces carat weight.

Refining

The process of purifying metals such as gold, silver or platinum by removing other metals and impurities. It is used on scrap and recycled jewellery.

Read more: Diamond Cavities and Chips

Report Check

A service to verify that a gemstone grading report is genuine and that its details match the issuing laboratory's records, usually via the report number.

Report number

The unique number printed on a gem grading report, used to look up or verify the report with the laboratory. Diamonds may also carry it as a laser inscription on the girdle.

Resale value

The amount you could expect to receive when selling a piece of jewellery second-hand. It is typically well below the original retail price or replacement value.

Reset

A gemstone that has been removed from its original mounting and placed into a new setting, or a piece of jewellery that has undergone this process.

Resetting

The process of taking a gemstone out of its existing mount and securing it in a new setting, often to update a ring's style or repair worn claws.

Read more: Tennis Necklaces Explained

Rolled gold

Jewellery made by bonding a layer of gold alloy to a base metal with heat and pressure. It is thicker and more durable than gold plating but not solid gold.

Rose cut

An old gemstone cut with a flat base and a domed top covered in triangular facets, resembling a rosebud. It is common in antique and vintage diamond jewellery.

Rough

A gemstone in its natural, uncut and unpolished state, as it comes from the mine or ground, before being shaped and faceted.

Rough diamond

An uncut, unpolished diamond as mined. It often looks like a dull, glassy or greasy crystal and is cut and polished to reveal its sparkle.

Rough yield

The proportion of a rough stone's weight that remains as a finished gem after cutting and polishing. Diamonds often yield less than half of the original weight.

Round brilliant

The most popular diamond cut, with a circular outline and 57 or 58 facets arranged to maximise brilliance and sparkle.

Rubellite

A pink-to-red variety of tourmaline. The finest stones have a strong, rich red or purplish-red colour that stays vivid in different lighting.

S

Salt and pepper diamond

A diamond with many small white and black inclusions, giving a speckled, grainy look. It is valued for its unconventional, rustic style rather than clarity.

Sandblasting (abrasive blasting)

A finishing technique that propels fine abrasive particles at a metal surface to create an even, matte or frosted texture.

Read more: Sandblasted Ring Finish

Satin (brushed) finish

A soft, non-reflective metal finish made by brushing the surface with fine abrasive to produce tiny parallel lines. It hides minor scratches better than high polish.

Satin finish

A smooth, low-sheen metal surface with a soft glow rather than a mirror shine, created by fine brushing or abrasion.

Saturation

The strength or intensity of a gemstone's colour. Highly saturated stones appear vivid, while low saturation looks greyish or brownish.

Scaife

The cast-iron polishing wheel, charged with diamond powder and oil, used by diamond polishers to grind and polish facets on diamonds.

Scanning spray

A temporary matte powder spray applied to shiny or reflective items, such as jewellery, so 3D scanners can capture the surface accurately.

Schiller

A metallic-looking sheen or glow that seems to shift as a gem is moved, caused by light reflecting from internal structures. It is seen in moonstone and labradorite.

Read more: Mokume Gane Rings Melbourne

Shank

The part of a ring that goes around the finger, also called the band. It supports the setting and affects comfort, strength and style.

Shared claw

A single claw or prong that holds two neighbouring stones at once, letting stones sit closer together and reducing the metal visible between them.

Shared-claw (shared-prong) setting

A setting where each claw, also called a prong, holds two adjacent stones. It allows stones to sit close together with minimal visible metal.

Shared-claw setting

A setting in which neighbouring stones are held by common claws. It gives a continuous sparkle with less metal showing, often used in eternity bands.

Shared-prong setting

A setting where one prong holds two neighbouring stones. It creates a continuous line of gems and uses fewer prongs than separate settings.

Shibuichi

A traditional Japanese alloy of copper and silver, usually about a quarter silver. It takes on soft grey patinas and is used in decorative metalwork and jewellery.

Read more: Mokume Gane Rings Melbourne

Shortwave UV

Ultraviolet light of about 254 nanometres, used in gemmology to see whether a stone fluoresces. Reactions can help identify gems or separate natural from synthetic ones.

Shortwave UV transmission

How much shortwave ultraviolet light passes through a stone. Gemmologists use it to help identify some gems, such as separating certain diamonds from simulants.

Read more: Types of Necklace Chains

Solitaire

A piece of jewellery, usually a ring, featuring a single gemstone, most often a diamond, with no other stones in the main design.

Solitaire setting

A ring setting that holds one centre stone, typically with claws or a bezel, on a plain band. It puts the focus entirely on the gem.

Read more: Labradorite

Spectroscopy

A gemmological testing method that studies how a stone absorbs or emits light. It helps identify gems, detect treatments and separate natural from synthetic stones.

Spessartine

A garnet variety in vivid orange to reddish-orange colours. Also called spessartite, it is valued for its bright colour and is a fairly durable gemstone.

Read more: Amber

Sulphide rosette

A flower-like cluster of tiny sulphide crystals, often seen in some gemstones such as synthetic or natural peridot. It is a recognisable inclusion used in identification.

Sum insured

The maximum amount an insurer will pay to replace or repair an item, as stated in the policy. For jewellery it should match a current valuation.

Sun spangles

Reflective, glittering disc-shaped fractures in some gemstones that look like tiny metallic flecks. They are often found in heated or treated stones, such as certain sapphires and sunstone.

Read more: Amber

Surface graining

Fine lines or ridges on a gemstone's surface that mark internal crystal growth planes. They can be visible on the facets of a polished stone.

Read more: Graining in Diamonds

Suspended setting

A setting where the gemstone appears to float, held by thin wires or hidden supports rather than a solid metal frame. It shows more of the stone but offers less protection.

Symmetry

How precisely a gemstone's facets and outline match each other. Good symmetry helps light reflect evenly and makes the stone look balanced and sparkly.

Symmetry grade

A rating on a grading report, from Excellent to Poor, of how well a diamond's facets are aligned and shaped. It affects how light moves through the stone.

Syngenetic inclusion

A crystal or other feature trapped inside a gemstone as it grew. It forms at the same time as the host stone and is a key clue to natural origin.

Synthetic

A material made in a lab with the same chemical composition and structure as its natural counterpart. It is not the same as an imitation, which only looks similar.

T

Tab claw

A flat, wide metal tab that folds over a gemstone's edge to hold it, often used on step-cut stones. It gives a modern look with a secure hold.

Table

The large, flat facet on top of a gemstone. It is the biggest facet and strongly affects how bright and clear the stone looks from above.

Table percentage

The width of a diamond's table as a percentage of its overall diameter. It influences brilliance and fire, with moderate values usually preferred in round diamonds.

Tantalum

A dense, dark grey, hypoallergenic metal used in some modern rings. It is very durable and corrosion resistant, and can be anodised in colours.

Taper

A gradual narrowing in width, such as a ring band getting thinner toward the back or a baguette stone narrowing along its length.

Tapered baguette

A narrow, rectangular step-cut gemstone that is wider at one end than the other. It is often used as side stones to frame a centre diamond.

Tapered band

A ring band that narrows from the top to the back, or from one side to the other. It can make a centre stone look larger and the ring more comfortable.

Tarnish

A dull or darkened layer that forms on metals like silver when they react with air, moisture or sulphur compounds. It can usually be removed with polishing.

Tax invoice

A document from a seller showing the details of a sale, including GST. In Australia, it is required for sales of $82.50 or more if the buyer asks for one.

Tennis bracelet

A flexible bracelet set with a continuous line of equal-sized gemstones, usually diamonds. It gets its name from a tennis star who famously lost hers on court.

Tennis necklace

A necklace with a continuous row of evenly sized gemstones, usually diamonds, set in a flexible chain. It is the necklace version of a tennis bracelet.

Read more: Tennis Necklaces Explained

Tension fracture

A crack in a gemstone caused by internal stress, often around an inclusion. It can open up further if the stone is knocked or heated.

Tension setting

A setting in which the band's spring pressure alone holds the gemstone in place, with small grooves cut into the metal. The stone appears to float between the ends of the band.

Tension-style setting

A setting that looks like a tension setting, with the stone seemingly suspended, but usually uses hidden supports or small cuts for extra security.

Thermal conductivity

How well a material moves heat. Diamond conducts heat unusually well, which is the basis of simple diamond testers.

Thermal conductivity tester

A handheld device that touches a gemstone with a heated probe to measure how quickly heat travels away. It helps tell diamonds from most imitations, but not from moissanite.

Thermal diamond tester

A small electronic tool that measures how fast heat moves through a stone to check if it is diamond. It cannot reliably separate diamond from moissanite.

Thermal shock

Damage caused by a sudden, large temperature change, such as plunging hot jewellery into cold water. Stones with inclusions or fractures are most at risk.

Thermal tester

A device that uses heat flow to help identify gemstones, mainly to separate diamond from imitations. Results should be confirmed with other tests.

Thin-film coating

A very thin layer applied to a gemstone's surface to change its colour or sheen, such as on mystic topaz. The coating can wear off with rough use.

Read more: Bracelet Size Guide

Toi et moi

A ring, French for 'you and me', with two stones set side by side, often diamonds or different gems, symbolising two people joined together.

Tone

How light or dark a gemstone's colour appears, ranging from very light to very dark. It is one part of describing gem colour alongside hue and saturation.

Topaz

A hard gemstone found in many colours, including colourless, blue, yellow and pink. Much blue topaz on the market is colourless topaz treated to change its colour.

Read more: Jade

Type I clarity

A gemstone clarity group for stones that are usually free of inclusions to the naked eye, such as aquamarine. Even good examples are expected to be very clean.

Type Ia

The most common type of natural diamond, containing nitrogen atoms in clusters or pairs. Many are colourless to pale yellow.

U

Ultrasonic cleaner

A machine that uses high-frequency sound waves in liquid to shake dirt from jewellery. It suits many hard stones but can damage fractured, treated or delicate gems.

Ultraviolet (UV) light

Light with wavelengths shorter than visible light. Gemmologists use it to see fluorescence in gems, which helps identify stones and some treatments.

V

V band

A ring band shaped with a V-shaped dip or point, usually to fit around a stone or to complement another ring.

V-claw

A claw with a pointed V-shaped tip, used to protect and secure the sharp corners of stones such as princess, marquise, pear and heart cuts.

V-prong

A prong shaped as a V to cover and protect a pointed corner of a stone, such as on a marquise, pear, princess or heart cut.

W

Wash

A thin surface coating or plating of a metal such as gold or silver over another metal. It is very thin and wears away quickly.

Read more: Bracelet Size Guide

Wrought metal

Metal shaped by hammering, rolling or drawing rather than casting. It is generally denser and stronger.

X

X-radiography

A test using X-rays to examine inside a gem, such as pearls, to reveal structure and tell natural from cultured pearls.

Y

Yellowness index

A measure of how yellow a material appears. In diamonds, it can help show how far a stone's colour moves from colourless.

Yield

The proportion of a rough gem that remains as a finished cut stone. A higher yield means less material is lost in cutting.

Z

Zachery treatment

A heat-and-chemical process used on turquoise to deepen its colour and make it harder and more polishable. It should be disclosed when selling the stone.

Read more: Zircon

Zoisite

A mineral family that includes tanzanite, its blue-violet gem variety, and green zoisite. Tanzanite is soft and sensitive to knocks and heat.