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A diamond grading report records what an independent laboratory measured about a specific stone. The fields that matter most to how the diamond actually looks are cut grade and carat weight. The field that matters most to proving the certificate belongs to your diamond is the report number, which should be laser-inscribed on the girdle of the stone.
Start here: does the certificate belong to this diamond?
Before reading any grade, establish that the paper and the stone are connected.
- Find the report number printed on the certificate.
- Ask the jeweller to show you the same number laser-inscribed on the girdle, the thin outer edge of the stone. It is invisible to the naked eye and readable under a loupe.
- Enter the report number on the issuing laboratory’s own website and confirm the grades match.
If the inscription is absent on a stone above roughly half a carat, or the number is not in the laboratory’s database, stop and ask why before going further.
The fields, and what each one means
Carat weight
The actual weight, measured to two decimal places, not an estimate. Note that a stone described as 0.98 carat is visually identical to a 1.00 carat and costs noticeably less, because pricing jumps at round numbers.
Colour
Graded D through Z, where D is colourless. D to F is colourless, G to J is near colourless, K onward shows visible warmth.
For most buyers G to H is the sensible place to sit. In a yellow or rose gold setting you can go further down the scale without it showing, because the metal casts warmth anyway.
Clarity
From FL (flawless) through IF, VVS1, VVS2, VS1, VS2, SI1, SI2 to I. The grades describe inclusions, which are natural features inside the stone.
The practical threshold is eye-clean: the point at which inclusions are not visible without magnification. For most stones that is around VS2. Paying for VVS1 buys you something only a loupe can see.
One exception: emerald and Asscher cuts have large open facets that show inclusions more readily, so it is worth going a grade or two higher on those shapes.
Cut
The grade that matters most, and the one most often overlooked. Cut measures how well the stone was proportioned and finished, which determines how it returns light.
A poorly cut diamond looks dull no matter how good its colour and clarity are. An excellently cut stone one colour grade lower will look better than a badly cut stone above it. If you compromise anywhere, do not compromise here.
Note that cut grades are given for round brilliants. Fancy shapes such as oval, pear and marquise often show polish and symmetry grades instead.
Polish and symmetry
Graded Excellent through Poor. Polish describes the smoothness of the facet surfaces; symmetry describes how precisely the facets align. Very Good or better on both is sensible. The difference between Excellent and Very Good is rarely visible.
Growth method
CVD or HPHT. This is specific to lab grown diamonds and simply records how the stone was produced. Neither is superior; see our guide on what a CVD diamond is.
Treatment
Some lab grown stones receive post-growth treatment to improve colour. If so, it must be disclosed on the report. Read this field. A treated stone is not a problem in itself, but it should be priced accordingly and you should know.
Measurements
Given in millimetres, for example 6.50 × 6.48 × 4.02. This is how large the stone actually is, which is not the same as carat weight. A shallow-cut stone can measure wider than a deep-cut stone of the same weight, and will look larger from above — though usually at the cost of brilliance.
Fluorescence
How the stone reacts under ultraviolet light. None to Faint is the usual preference. Strong blue fluorescence can make a stone appear slightly hazy in direct sunlight, though on lower colour grades it can also make the stone look whiter. Mostly a minor consideration.
What is not on the certificate
A grading report describes the stone only. It says nothing about:
- the gold, its purity or its weight
- whether the setting is well made
- what the piece is worth
- whether the price you were quoted is fair
For the gold, look for the BIS hallmark, which is a separate certification covering purity. Ivana Jewels uses BIS hallmarked 14kt and 18kt gold.
Reading two certificates side by side
When comparing stones, compare in this order:
- Cut grade — eliminate anything below Very Good
- Carat weight — the size you actually want
- Clarity — down to eye-clean, no further
- Colour — down to the point it shows in your chosen metal
- Measurements — which of two similar stones looks larger
And then look at both stones in daylight. Certificates narrow a shortlist; they do not choose for you. Two stones with identical grades can look different.
Keep it safe
Replacing a lost certificate at buyback or exchange costs ₹2,000 per carat for IGI and ₹1,000 per carat for SGL at Ivana Jewels. Photograph it on the day you buy and store the image somewhere durable.
Frequently asked questions
Which laboratory issued my certificate?
It is printed on the report. Ivana Jewels uses IGI or SGL on every stone. See our comparison of IGI vs SGL certification.
My stone has no inscription. Is that a problem?
On smaller stones, inscription is not always applied and that is normal. Above roughly half a carat you should expect one. Without it, the certificate cannot be tied to that specific stone.
Can a certificate be faked?
Printed documents can be. This is exactly why you verify the report number on the laboratory’s own website rather than trusting the paper in front of you.
Does a better certificate mean a better diamond?
It means a better-documented diamond. Two stones with identical reports can look different, because grading has tolerances and cut quality within a grade varies. Always look at the stone.
Do small accent stones come with certificates?
Generally not individually. Certification is usually applied to the centre stone. Ask what is covered before assuming every stone in a piece is documented.
Bring a certificate to any of our eleven showrooms and we will read it through with you, in Delhi, Mumbai, Ahmedabad, Surat, Pune, Thane, Nagpur, Noida, Hyderabad and Mohali, open 10:30am to 9pm every day.
