How to Read a Diamond Report

A grading report looks official, which discourages questions. How a jeweller reads one line by line, which grades deserve your budget, and the section most buyers skip.

A grading report arrives looking official, which is precisely the problem. Official documents discourage questions.

Here is how we read one with a client sitting across the table.

Start at the bottom, not the top

Most people read the grades first. We read the identification first, the measurements, the shape, the report number. Then we check the number laser-inscribed on the stone matches the number on the paper.

A report describes one specific diamond. Confirming that it describes this diamond takes a moment and is the whole point of having it.

Check the report is real, and current

Every major laboratory publishes a free online lookup. You enter the report number and the laboratory shows you its own copy of the record.

Do it while you are sitting there. It takes under a minute and it confirms three things at once: that the report exists, that the grades on the paper match the grades in the database, and that the document in your hand has not been altered.

A printed certificate is a photocopy of a fact. The laboratory's own record is the fact.

Then the grades, in order of consequence

Cut first, where it is given. Colour and clarity next, with the understanding that both scales extend well past what an unaided eye can detect.

The most common mistake we see is a buyer paying a significant premium to move from one clarity grade to the next when neither inclusion is visible without magnification. That money buys a better line on a document. It does not buy a better-looking ring.

Read the plot as a map, not a verdict

The diagram of the stone with symbols scattered across it alarms people. It should not. It is a map of identifying characteristics, drawn at magnification, and its main job is to make the stone identifiable rather than to condemn it.

What matters is not how many marks there are but where they sit and what kind they are. An inclusion under the table, in the middle of your line of sight, matters more than one near the girdle that a prong will cover. Something that breaks the surface matters more than something sealed inside.

Ask which marks on the plot you would actually be able to find, and where. Most of the time the honest answer is that you would not find them at all.

The line most people skip

Comments. It sits at the bottom in small type and it can materially change what you are looking at, treatments, additional clouding, characteristics not shown in the plotted diagram.

Read the comments.

Fluorescence, and why it is not a grade

Most reports note whether the stone glows under ultraviolet light, and to what degree. Buyers frequently read this as a fault.

It is a description, not a demerit. Strong fluorescence can make a faintly tinted stone look whiter in daylight, and in some stones it can contribute a slightly hazy appearance. Both effects are real and neither is universal.

The only sensible way to treat it is to look at the stone in daylight and decide whether you like what you see.

What a report cannot do

It cannot tell you whether the stone is beautiful. Two diamonds with identical grades can perform noticeably differently, particularly in fancy shapes.

It also cannot tell you what the stone is worth. A grading report describes; it does not appraise. Valuation is a separate document produced for a separate purpose, usually insurance, and treating one as the other leads to disappointment in both directions.

The report tells you what you are buying. Your eye tells you whether you want it. Use both, in that order, and do not let the paper overrule the stone in front of you.

Book a complimentary design consultation at our Kuala Lumpur atelier: 010-766 7448 · hq@cgarden.com.my

C'Garden is an independent bespoke jeweller in Kuala Lumpur. We are not affiliated with, endorsed by, sponsored by or certified by any organisation, laboratory or brand named in this article. Third-party names are used only to refer factually to those organisations and their published standards. All text and imagery in this article is original work created by C'Garden.

Reference

Gemological Institute of America. (n.d.). How to read a GIA diamond grading report. GIA 4Cs. https://4cs.gia.edu/en-us/blog/how-to-read-a-gia-diamond-grading-report/