Compare cut, color, clarity and carat together. One high grade on its own does not make a great stone, and cut in particular shapes how the other three come across. Here is what each grade actually means.
- ExcellentMaximum light return
- Very GoodExcellent light return
- GoodLimited light return
- FairReduced sparkle
- PoorSevere light loss
How to choose · Within your budget, aim for Excellent–Very Good. A lower cut makes a stone of the same carat look smaller and darker.
ColorlessLight yellow
How to choose · G–H looks colorless to the naked eye and costs 20–30% less than D–F. For a white gold or platinum setting, we recommend F or higher.
Clarity
A grade of the type, location and visibility of inclusions and surface features, in eleven steps from FL to I3.
- FL / IFFlawless even under 10× magnification
- VVS1 / VVS2Inclusions even experts struggle to find
- VS1 / VS2Clean to the naked eye
- SI1 / SI2Visible under magnification, usually eye-clean
- I1 / I2 / I3Inclusions visible to the naked eye
Minimum grade for an eye-clean stone| Under 0.5 ct | SI1 or higher |
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| 0.5–1 ct | VS2 or higher |
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| 1 ct and above | VS1 or higher |
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Carat
A measure of weight, not size. One carat is 0.2 grams, and the same weight can look different depending on the cut.
- 0.3ct4.3mm
- 0.5ct5mm
- 0.7ct5.6mm
- 1ct6.5mm
- 3ct9.1mm
How to choose · Diameters are for a round brilliant. A 1 ct stone cut wide and shallow looks larger; one cut narrow and deep looks smaller.
What to check on the grading report
- Report number
- Look the number up on the issuing lab's website to confirm the report is genuine.
- Girdle inscription
- Check that the number inscribed on the girdle matches the report number.
- Measurements
- Stones of the same carat can differ in diameter, so read the mm measurements alongside the grades.
- Video
- Inclusion placement and sparkle are easier to judge on video than in still images.
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