How to Read (and Verify) a Laboratory-Grown Diamond Certificate
Report number, origin statement, the 4Cs, growth method and inscription — what each line means and how to check it yourself in two minutes.
- A grading report is issued by an independent laboratory, not the seller.
- It should clearly say the stone is laboratory-grown, and give its 4Cs and a unique report number.
- Verify it on the lab's own website, then match the number laser-inscribed on the stone.
A diamond certificate, more accurately called a grading report, is the single most useful document in your purchase. It tells you what the stone is, written by someone with no interest in selling it to you. Here's how to read one line by line, and how to check it's genuine.
Who issues it
Independent gemmological laboratories examine the stone under controlled conditions and record what they find. Laboratories widely used for laboratory-grown diamonds in India include the International Gemological Institute (IGI), the Gemological Institute of America (GIA) and Solitaire Gemmological Laboratories (SGL). Layouts differ, but the core information is the same.
A "certificate" printed by the shop itself is not the same thing. It may be accurate, but no one independent has checked it.
Reading the report, line by line
Report number
A unique number for your stone. It's the key to everything else: you use it to look the report up online, and it's usually laser-inscribed on the stone.
Origin: "laboratory-grown"
The report should state plainly that the diamond is laboratory-grown (some labs also use "laboratory-created" or print "LG" before the report number). If a report for a laboratory-grown stone doesn't say so, walk away. In India, the BIS terminology standard requires laboratory-grown diamonds to be described as such.
Shape and cutting style
The outline (round, oval, pear, marquise, heart, and so on) and the facet arrangement, for example "round brilliant".
Measurements
Length × width × depth in millimetres. Useful for two things: picturing the actual size, and confirming the stone in your hand matches the report.
Carat weight
Weight, not size. One carat is 0.2 grams. Two stones of the same weight can look different in size depending on how they're cut.
Colour grade
On a scale from D (colourless) through E, F, G, H and onwards. Many laboratory-grown diamonds fall in the D–H range. Once set, especially in yellow or rose gold, neighbouring grades are very hard to tell apart.
Clarity grade
How many tiny internal features (inclusions) and surface marks the stone has, seen under 10× magnification:
- FL / IF — flawless / internally flawless
- VVS1, VVS2 — very, very slightly included
- VS1, VS2 — very slightly included
- SI1, SI2 — slightly included
- I1–I3 — included
VS stones generally look clean to the naked eye.
Cut, polish and symmetry
Cut describes how well the stone's proportions return light — it's the biggest factor in sparkle. Polish and symmetry describe the finishing. "Excellent" or "Ideal" is the top of the scale at most labs.
Fluorescence
How the stone glows under ultraviolet light. "None" or "Faint" is most common and has little effect on appearance.
Growth method and treatment
Many reports note whether the stone was grown by CVD or HPHT, and whether it had any post-growth treatment (a process used to improve colour after growth). "As grown" means no such treatment was detected. Treatment isn't necessarily bad, but it should always be disclosed.
Inscription
The report number (sometimes with a lab logo or "LG" prefix) laser-inscribed on the stone's girdle, the thin outer edge. It's invisible to the naked eye but readable under a jeweller's loupe.
How to verify a report in two minutes
- Type the lab's website address yourself. Don't rely on a link or QR code sent by anyone, including the seller.
- Open its "verify report" page and enter the report number.
- Compare every detail: shape, measurements, carat, colour, clarity, cut and the origin statement should match the paper report exactly.
- Match the inscription. Ask the seller to show you the girdle inscription under magnification (a close-up photo or video works) and check it against the report number.
Why the last step matters: the International Gemological Institute has publicly reported a case where a laboratory-grown stone carried an inscription copied from a natural diamond's report. The number looked right; the stone wasn't. Checking measurements and features against the report, and buying from sellers who welcome checks, protects you.
What isn't usually certified
Small accent stones (melee) around a centre stone, or in pavé bands and clusters, are usually too small to grade individually. A trustworthy seller will tell you their total carat weight and the colour and clarity range instead.
Don't forget the gold
The diamond report covers the stone only. For the metal, look for the BIS hallmark: the BIS logo, a purity mark such as 18K750 or 22K916, and a six-character HUID code you can verify in the BIS CARE app.
Want to see what a real report looks like before you order? Our certification page explains how we handle it, or ask us on WhatsApp and we'll walk you through one.
Quick answers
How do I check if a diamond certificate is genuine?
Type the report number into the 'verify report' page on the issuing laboratory's own website and check that the shape, measurements, carat and grades match your paper report. Then check that the number laser-inscribed on the stone matches too.
What does 'as grown' mean on a report?
It means the laboratory found no post-growth treatment, such as a heat or pressure process used to improve colour after the diamond was grown.
Do small diamonds come with certificates?
Usually not individually. Accent stones (melee) are too small to grade one by one economically, so certificates normally cover the centre stone or stones.
Planning a piece?
Tell us the occasion and a rough budget. You'll get an approximate price and a CAD design before anything is made.
