How to read a diamond listing

One carat is 0.20 grams. Two 1 carat rounds can look different because the cut spreads that weight into a wider or narrower face. On a listing, carat is the measured weight. The millimeter measurements tell you the size you will actually see.

A round brilliant of about 6.4 to 6.5 mm is a typical 1 carat. The chart on this page is a guide, not a promise. The listing’s own measurements override it.

For a round brilliant, laboratories grade the cut Excellent, Very Good, Good, Fair, or Poor. Excellent means the angles send light back out of the top. A lower cut can look smaller and sleepier even at the same carat weight.

Ovals, emerald cuts, cushions, and pears are graded on polish and symmetry, not on a single cut grade. For those, look at length-to-width, a bow-tie in the middle, and whether the outline is even. We describe that on the listing instead of hiding it in a photo.

For a round, a table around 54–58% and a depth around 59–62.5% is the usual range for an Excellent cut. Outside that, the stone can still be attractive. The listing shows the numbers either way.

D is colorless. The scale walks toward tint: E, F, G, H, I, J, and on. In a white metal, F and G look colorless to almost everyone. H is still bright. I and J show a warm tint once the stone is over a carat, especially in yellow or rose gold, where that tint can look intentional.

Set in yellow gold, a G and a J can be hard to tell apart. Set in platinum, the difference shows. The listing names the metal so you can judge the letter against it.

Clarity describes inclusions, the internal marks. VS1 and VS2 are very slightly included. In a finished ring they are almost always clean to the naked eye. SI1 can be clean to the eye if the inclusions are off to the side. SI2 and I1 often show, and we will say if they do.

“Eye-clean” is not a grade. If we use it, the laboratory grade is still printed next to it.

Fluorescence is a glow under ultraviolet light. None and Faint do not change the stone in daylight. Medium and Strong can make a lower color look whiter, and in some stones they make it look oily. The listing states the level.

Polish and symmetry are Excellent, Very Good, or Good. They describe the surface and the outline, not the body color.

If a stone has a grading report, the laboratory and the report number are on the listing. GIA, IGI, and HRD are the ones we use. The report describes the diamond. It is not an appraisal of the setting, and it is not a valuation of what you should pay.

A stone without a report is labelled as such. We do not invent a grade.