Certification
How to read your IGI certificate
Every Stacked&Co diamond arrives with an IGI report, which is an independent laboratory's word on exactly what your stone is. Here is what every line means, and how to verify it yourself in under a minute.
What an IGI report is
The International Gemological Institute (IGI) is one of the world's major independent diamond grading laboratories and the leading certifier of lab-grown diamonds. Independent is the important word: IGI graders assess the stone, not the seller, so the grades on your report were determined by people with no stake in the sale.
When you buy a certified diamond, you are not taking the jeweller's word for the colour, clarity, cut, and carat. You are holding a laboratory's measurement of all four, tied to your specific stone by a report number inscribed on the diamond itself.
The report, line by line
Report number
The unique ID of your diamond's report. It is also laser-inscribed on the girdle (the thin outer edge) of the stone, far too small to see without magnification, which permanently ties this exact diamond to this exact certificate.
Description
States what was graded, for example "Lab Grown Diamond". IGI grades lab-grown and mined diamonds on the same scales, and the report always says plainly which one you are holding.
Shape and cutting style
The outline of the stone (round, oval, cushion, emerald, pear, princess) and how its facets are arranged, such as brilliant cut. This is the silhouette you chose.
Carat weight
The weight of the diamond, measured to two decimal places. One carat is 0.2 grams. Weight is not the same as visual size: a well-cut diamond can look larger than a heavier, deeper-cut one.
Colour grade
Graded from D (completely colourless) onwards through the alphabet as warmth increases. D, E, and F read as icy white; G to J read white with warmth only a grader would catch.
Clarity grade
How free the stone is of internal characteristics (inclusions) and surface marks (blemishes), from Flawless down through VVS, VS, and SI grades. Most grades on this scale describe things you will never see without a microscope.
Cut grade
How well the proportions and angles return light, typically Excellent to Poor on round brilliants. Cut is the C that does the sparkling, so treat this line with respect.
Polish and symmetry
Two finishing grades: how smoothly the facets were polished, and how precisely they align with each other. Excellent and Very Good are what you want to see, and what we order.
Fluorescence
Whether the stone glows softly under ultraviolet light, from None to Strong. At most grades this has no visible effect in daylight; it is a characteristic, not a flaw.
Measurements and proportions
The stone's dimensions in millimetres plus its table and depth percentages, often with a plotted diagram of its facets and any inclusions. This is the fingerprint section: no two diamonds plot the same.
Verify it yourself
This is the part we genuinely encourage. Take the report number from your certificate and check it against IGI's own database using the Verify Your Report tool on igi.org. Enter the number and IGI shows you the report it holds for that stone, straight from the source. If you are ever buying a certified diamond, from us or from anyone, this sixty-second check is the strongest due diligence available to you.
Keep the certificate with your invoice once your ring arrives. Together they document exactly what you own, which matters for insurance. We cover that in insuring your engagement ring in South Africa.
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