Diamond Valuation vs Certificate: The Australian Guide to Grading Reports and Jewellery Valuations

What is a diamond certificate?

A diamond certificate is the everyday name for a grading report: a document issued by an independent gemmological laboratory after it has examined a loose diamond. The labs themselves prefer the word report, because the document records their expert opinion of the stone on the day it was graded. It is a description, not a valuation. Our overview of diamond certificates and jewellery reports sets out every document type you are likely to meet.

A full report for a diamond of about 1 carat usually records:

• Identity: that the stone is diamond, and whether it is natural or laboratory-grown.
• Carat weight: measured on a precision scale to 0.01 carat.
• Colour grade: on the D (colourless) to Z (light yellow or brown) scale.
• Clarity grade: from Flawless (FL) to Included (I3), based on inclusions (internal features) and blemishes (surface marks) seen at 10× magnification.
• Cut, polish and symmetry: an overall cut grade for round brilliants, plus polish and symmetry grades for all shapes.
• Measurements and proportions: length, width and depth in millimetres, table and depth percentages.
• Fluorescence: how strongly the stone glows under ultraviolet light, from None to Very Strong.
• Plotting diagram: a map of where the main inclusions sit, and any laser inscription on the girdle (the thin outer edge).

If you have a report in front of you now, our walk-through on reading a GIA report line by line explains each box, and the IGI natural diamond report explained covers the layout IGI uses. Any unfamiliar term is defined in our plain-English jewellery glossary.

Which labs issue diamond grading reports?

Several laboratories grade diamonds, and they are not interchangeable. Grading is a skilled judgement, and labs differ in how strictly they apply the colour and clarity scales. A valuer will take the issuing lab into account, because the same grades from a stricter lab describe a better stone.

For a fuller side-by-side, see how GIA, IGI and HRD reports differ and our wider comparison of the main grading laboratories. Individual lab guides cover the HRD report format, AGS reports and their light performance grades, GCAL light performance imaging and what to know before trusting a GSI or EGL report.

What is a jewellery valuation in Australia?

A jewellery valuation is a written document, prepared by a qualified valuer, that describes a finished piece of jewellery and states a dollar value for a stated purpose. In Australia that purpose is most often insurance, so the figure is usually a replacement value: the approximate cost, in AUD and including GST, of replacing the item with one of like kind and quality from a retail jeweller today.

Australia does not have a single government licence for jewellery valuers. Many valuers hold gemmology qualifications (for example from GIA or the Gemmological Association of Australia) and some are registered with the National Council of Jewellery Valuers, which sets standards for its members. It is reasonable to ask any valuer what qualifications and registration they hold before you book. Our guide to what an insurance valuation covers and how insurers use it goes deeper into the insurance side.

A thorough valuation should include:

• A full description: item type, style, setting style, number of stones and how they are held.
• Metal: type and fineness (for example 18 carat yellow gold or 950 platinum), confirmed by testing and hallmarks, plus the total weight in grams.
• Each significant stone: identity, shape, measurements, estimated or recorded carat weight, colour and clarity, and whether it is natural, lab-grown or a lab-created or treated gem.
• Report details: the lab and report number, if the diamond has one, and whether the inscription was checked.
• Photographs: clear images of the piece, useful for identification after a loss.
• Value, purpose and date: the dollar figure, what kind of value it is and when it was assessed.
• Valuer's name, qualifications and signature.

Diamond valuation vs certificate: what is the difference?

The simplest way to think about it: a grading report answers what is this diamond? and a valuation answers what is this piece of jewellery worth, and for what purpose? Most engagement rings need both.

The two documents work together. A valuer who can read the report number on the girdle and match it to the report can value the diamond with much more confidence than one estimating grades through a setting. Without a report, a mounted round brilliant's weight is estimated from its measurements, using a formula such as diameter² × depth × 0.0061 (in millimetres). That is usually close, but it is still an estimate, and the valuation should say so.

What types of jewellery valuation are there?

The same ring can carry quite different values depending on why it is being valued. That is not inconsistency; each figure answers a different question. A valuation should always state which value it gives.

Estates and family law matters need a market value, not a replacement value, and the valuer may need to sign a statement about their independence. Our guide on valuations for deceased estates and family law settlements explains what lawyers and executors usually ask for.

A higher insurance figure is not automatically better. Many policies replace the item through the insurer's own suppliers rather than paying out the full sum, and a higher valuation usually means a higher premium. An accurate figure, clearly described, protects you best. Check your own policy wording for how it settles jewellery claims.

Why is a diamond grading report not a jewellery valuation?

It is common to assume a GIA or IGI report is enough for insurance. In most cases it is not, for four reasons:

• No price: laboratories deliberately avoid putting a value on a stone. They grade; they do not price.
• Diamond only: the report ignores the metal, the setting, side stones and the work that went into the ring, which together can be a large share of the replacement cost.
• No link to the ring: a report describes a loose diamond. On its own it does not prove that this diamond is the one in your ring today.
• No market context: diamond prices move, and lab-grown prices in particular have fallen a great deal in recent years. A report from five years ago says nothing about today's replacement cost.

The link between report and stone is usually a laser inscription: the report number written microscopically on the girdle, readable at about 10× magnification. It is useful, but it can be polished off or copied, so a valuer also checks the measurements, weight estimate and inclusion pattern against the report's plot. Our page on what a laser inscription proves and what it cannot explains the limits.

The reverse is also true: a valuation is not a grading report. A valuer grading a mounted stone cannot see it as well as a lab can with the stone loose, so their grades are an informed estimate. If you are buying a diamond, a report from a respected lab is the document that tells you what you are paying for. See the case for certified over uncertified diamonds for how the two compare at purchase.

How are lab-grown diamonds and origin reports treated in a valuation?

Lab-grown diamonds are real diamond, with the same hardness (10 on the Mohs scale) and refractive index (about 2.42) as natural diamond. They cannot be told apart by eye, so a valuation must state clearly that the stone is laboratory-grown, using the report and, where needed, testing equipment. Their replacement values are much lower than for natural diamonds of the same grades, and their retail prices have moved quickly, so a lab-grown valuation dates faster.

Natural diamonds are valued on their grades and on current retail replacement cost, not on any idea of future gain. Neither type should be thought of as an investment; the valuation simply records what it would cost to replace the piece today.

Some natural diamonds also come with an origin report, which records the country or mine the rough came from, based on records tracked from the mine through cutting. Provenance can matter to owners, and for rare categories it can affect value, so a valuer will note it. Our guide to how diamond origin reports are produced and checked covers what these documents can and cannot confirm.

How often should you update a jewellery valuation?

A valuation is a snapshot of a price on one date. Gold and platinum prices, diamond prices, exchange rates and making costs all shift, so the replacement figure drifts away from reality over time. Many valuers and insurers suggest updating every 2–3 years, sooner if the price of gold has moved sharply or if the piece contains lab-grown diamonds.

• After a big metal price movement: gold content can be a large part of a heavy band or chain.
• After any change to the piece: resizing, a new setting, added stones or a remodel.
• When your insurer asks: some policies require a recent valuation for items over a set value.
• For lab-grown pieces: falling retail prices can leave you insured for more than replacement would cost.

Our guide on when and how often to revalue jewellery goes through each trigger in more detail, including what an updated valuation usually costs.

Diamond valuation vs certificate: which do you need, and how do you get a valuation?

If you are choosing a diamond, you need a grading report from a respected lab. If you are insuring, dividing or inheriting a piece, you need a valuation for the right purpose. If you own a diamond ring, you will usually want both, kept together. Valuations in Australia commonly cost somewhere around AUD $80–$250 per item, depending on complexity and the valuer, so ask for a quote first.

1. Decide the purpose. Insurance replacement, market value for an estate or family law, or resale. Tell the valuer up front.
2. Gather your documents. Bring grading reports, receipts, previous valuations and any origin or lab-grown paperwork.
3. Check the valuer. Ask about gemmology qualifications and professional registration, and whether they work independently of any sale.
4. Have the piece cleaned and inspected. Loose or worn claws are best found before the valuation, not after a loss.
5. Read the draft carefully. Confirm every stone is described, lab-grown stones are disclosed, the report number is matched and the type of value is stated.
6. Store copies safely. Keep a digital copy and a paper copy away from the jewellery, and send your insurer what they ask for.
7. Diarise the update. Set a reminder for 2–3 years, or sooner after any change to the piece.