Natural vs Lab-Grown Gemstones for Engagement Rings: The Australian Guide

What is the difference between natural and lab-grown gemstones?

A natural gemstone is a mineral (or, for pearl and amber, an organic material) that formed in nature, with no human help beyond mining, cutting and polishing. A lab-grown gemstone, usually called lab-created or synthetic in the gem trade, is grown in a laboratory and has essentially the same chemical composition, crystal structure and physical properties as its natural counterpart. A lab-created sapphire is corundum, aluminium oxide (Al₂O₃), exactly like a sapphire dug from the New England fields of New South Wales.

So, are lab-created gemstones real? Yes. A lab-created ruby is real ruby in the mineral sense; it simply was not mined. What it is not is natural, and the law requires that difference to be disclosed clearly every time the stone is described or sold.

A simulant is something else again: a material that only looks like the gem. Blue glass, cubic zirconia and synthetic spinel have all been used to imitate sapphire. A simulant can be natural or man-made, but it is not the gem it imitates. Our guide to the difference between natural, synthetic and simulant gems goes into the labels in more detail. The categories you will see on reports and listings:

• Natural: formed in the earth, cut and polished only.
• Natural, treated: formed in the earth, then improved, for example heated sapphire or oiled emerald. Very common and acceptable when disclosed.
• Lab-created or synthetic: same material as the natural gem, grown in a laboratory. For diamonds the usual term is lab-grown.
• Simulant or imitation: a different material that looks similar, such as cubic zirconia imitating diamond.
• Cultured: used for pearls grown by a living mollusc after a person inserts a nucleus or a piece of mantle tissue. These are not lab-grown.

You can see the full range of natural and lab-created stones in our coloured gemstones and birthstones collection, and every technical term in this guide is explained in our A–Z jewellery glossary.

How are natural and lab-created gemstones formed?

Natural gems need a rare meeting of the right chemistry, heat, pressure and time. Sapphire and ruby crystallise in certain metamorphic and igneous rocks; most eastern Australian sapphires were carried to the surface in basalt eruptions and later weathered into river gravels. Emerald is rarer still, because it needs beryllium and chromium or vanadium, elements that seldom occur together. Diamonds form roughly 150–200 km down in the mantle, a story told in our page on how natural diamonds form deep in the earth.

In a laboratory the same crystals are grown in weeks or months. The method matters, because it leaves its own clues inside the stone and affects the price.

Flame fusion is the oldest and cheapest method; Auguste Verneuil's process was producing lab-created rubies commercially in the early 1900s. Flux and hydrothermal stones take far longer to grow and look more like natural crystals inside, so they cost more. The same high-pressure, high-temperature equipment used to grow diamonds is also used to improve the colour of mined stones, which is explained in our guide to HPHT-treated natural diamonds.

Which gemstones are hard enough for an engagement ring?

An engagement ring is knocked, scraped and splashed every day, so durability matters more than anything else. Three properties decide it. Hardness (the Mohs scale, 1–10) is resistance to scratching; household dust contains quartz at 7, so anything below 7 will slowly dull. Toughness is resistance to chipping and breaking, which hardness does not predict. Stability is resistance to heat, light and chemicals.

The important point for this comparison: a lab-created gem has the same hardness and toughness as the natural one. Natural vs lab-created makes no difference to wear; the choice of gem does. The hardest gemstones for engagement rings, with their lab-created status:

Garnet is a lovely, affordable stone, but at 6.5–7.5 it suits rings worn with some care; our guide to natural garnet and garnet jewellery covers the different garnet species. YAG and GGG are laboratory-made materials with a garnet crystal structure, but they are simulants, not lab-created versions of the garnets you see in jewellery. Pearls are soft and organic, and the natural versus cultured question works differently, as explained in how natural and cultured pearls differ.

How do natural vs lab-grown gemstones compare for engagement rings?

Side by side, natural vs lab-grown gemstones differ in origin, rarity, inclusions, treatments and price, but not in what they are made of.

The rarity gap widens fast with size: a clean, well-coloured natural sapphire over 3 carats is far scarcer than a 1 carat stone, the same pattern shown in our page on how natural diamond rarity climbs with carat weight. Lab-created stones are not limited in that way, so large sizes cost relatively little.

Neither type should be bought as an investment. Fine natural stones can keep some secondhand value, but resale prices are well below retail and depend on the market at the time; our article on how natural diamond prices have moved over the years shows how uneven that can be. The same thinking applies to diamonds, covered fully in our natural and lab-grown diamond comparison.

Natural sapphire vs lab-created sapphire, ruby and emerald: what's different?

Each gem has its own pattern of natural and lab-created features. These are the ones I look at first with a 10× loupe and a microscope.

• Sapphire: natural stones often show silk (fine rutile needles crossing at 60°), liquid 'fingerprints' and straight, angular colour bands following the hexagonal crystal. Flame fusion lab-created sapphire shows curved striae (curved growth lines, like the grooves on a record) and gas bubbles. A lab-created sapphire engagement ring is identical in wear to a natural one, with a refractive index of about 1.76–1.77 in both.
• Ruby: natural rubies often contain silk, crystals and healed fractures, and most are heated. Lab-created rubies may show curved lines, flux veils or almost no inclusions at all, and their colour can glow more strongly under ultraviolet light.
• Emerald: natural emeralds almost always have inclusions, known as the jardin ('garden'); Colombian stones can show three-phase inclusions (a cavity holding liquid, gas and a tiny crystal). Most are treated with oil or resin. Lab-created emeralds show flux veils or chevron-shaped hydrothermal growth, and are usually untreated. A lab-created emerald engagement ring still needs the same careful setting, because emerald is brittle whatever its origin.
• Alexandrite: natural alexandrite with a strong colour change (green in daylight, red-purple under warm light) is very rare and expensive. Most alexandrite in jewellery is lab-created.
• Spinel: lab-created spinel was long used to imitate other gems, such as aquamarine. Natural spinel in red, pink and blue is now valued in its own right.
• Moissanite: natural moissanite is extremely rare, so jewellery moissanite is lab-created silicon carbide. It is sold as a diamond alternative, with a refractive index of about 2.65–2.69, higher than diamond's 2.42.

Where do Australian natural gemstones come from?

For many Australian couples, a home-grown stone is the strongest reason to choose natural. A lab-created gem has a manufacturer; a natural gem has a place.

• Sapphire: the New England fields around Inverell and Glen Innes in New South Wales, and the central Queensland gemfields around Anakie, Rubyvale and Sapphire. Australian sapphires are often deep, inky blue, and Queensland is known for green, yellow and parti-colour sapphires (two or more colours in one stone).
• Opal: Australia supplies most of the world's precious opal: black opal from Lightning Ridge in New South Wales, light opal from Coober Pedy and Andamooka in South Australia, and boulder opal from western Queensland. Opal is soft, so it suits a bezel-set ring worn with care.
• Pink diamond: the Argyle mine in Western Australia produced most of the world's pink diamonds until it closed in 2020.

Origin is usually stated by the seller rather than proven, though labs can give an opinion on country of origin for sapphire and ruby for an extra fee. If an Australian origin matters to you, ask what supports it.

How can you tell if a gemstone is lab-created?

Not by eye, and not with simple tests. Because the material is the same, a lab-created sapphire gives the same refractive index, specific gravity and hardness as a natural one. Identification relies on what is inside the stone and on laboratory instruments.

• Magnification: curved striae, gas bubbles and flux remains point to lab origin; silk, natural crystals and angular zoning point to natural origin.
• Ultraviolet fluorescence: some lab-created rubies and emeralds glow more strongly than natural stones; this is a clue, not proof.
• Spectroscopy: labs measure how a gem absorbs light and which trace elements it contains, which separates difficult stones.
• The report: an independent lab report should say natural or synthetic, and list any treatments.

Diamonds follow the same logic. A handheld diamond tester can screen for diamond (thermal-only models can pass moissanite) but cannot tell natural from lab-grown, as explained in what a diamond tester can and cannot detect. Labs use fluorescence imaging and spectroscopy, described in how gem labs separate mined and lab-grown diamonds, and the result appears on the certificate; see how natural and lab-grown diamond reports differ. Some features can only occur in mined stones, such as indented naturals dipping below the surface and original crystal skin left on the girdle.

How much do natural vs lab-grown gemstones cost in Australia?

Price is the biggest practical difference. Lab-created gemstones prices in Australia depend mainly on the growth method; natural prices depend on colour, clarity, size, treatment and origin, and rise steeply for fine stones.

These are broad ranges only; the low end of each lab-created range is usually flame fusion, the high end flux or hydrothermal. Unheated natural sapphires and rubies, and untreated emeralds, sit well above the natural ranges shown. For diamonds in detail, see our current Australian lab-grown diamond prices.

What setting suits a gemstone engagement ring?

Whether the stone is natural or lab-created, the setting does the protecting. Coloured gems are also cut deeper than diamonds to hold colour, so the setting needs enough height for the pavilion (the lower half of the stone).

• Sapphire, ruby, moissanite, alexandrite: four or six claws are fine for daily wear.
• Emerald: a bezel, or claws with a protective halo, guards its corners; avoid ultrasonic cleaners.
• Opal, tanzanite, garnet: a full bezel and a lower profile reduce knocks.
• Metal: platinum or 18 carat gold claws last longer than thin 9 carat claws on a daily ring.

How do you choose a natural or lab-created gemstone for your ring?

1. Pick the gem for durability first. For everyday wear, aim for Mohs 8 or higher with good toughness; sapphire and ruby are the safest coloured choices.
2. Decide what origin means to you. If a stone formed in the earth, or in Australia, matters, choose natural; if size and colour for the budget matter more, consider lab-created.
3. Set a budget range. Compare like with like: method for lab-created, treatment and origin for natural.
4. Ask for written disclosure. Natural or lab-created, and any treatment, should be stated on the invoice.
5. Check the report. For natural stones of any real value, an independent lab report confirms origin and treatment.
6. Plan the setting. Match the claws or bezel to the gem's toughness before you commit.