What does the “table” and “depth” on a report tell me about sparkle?

ZKZ Editorial TeamMain answer · Product & gemmology desk

Table and depth describe a stone's proportions, and proportions affect how it handles light. But they are not a score for sparkle. For round brilliants a laboratory gives a cut grade, and for fancy shapes GIA says there is no internationally accepted system for cut. We could not verify target percentages and do not give any.

What we verified

Fact GIA says cut grades are given only to round brilliant diamonds, because they are the only cut with standardized facets, and that all other shapes are fancy shapes.

Fact GIA says proportions impact face-up appearance, that there is a nearly unlimited combination of proportions, and that each grade range represents a range of proportion sets, leaving room for personal preference.

Fact GIA says the table is the large flat facet on top of the diamond, and that the major components of a round brilliant are crown, girdle and pavilion.

Fact GIA says an internationally accepted system for visually evaluating the appearance of fancy-cut diamonds does not exist at this time.

How to use the report

Our advice For a round brilliant, start with the cut grade, then look at the stone in video or in person.

Our advice For fancy shapes, compare photographs and light-performance videos from the seller.

It depends Two stones with the same table and depth can look different, and two with different numbers can look similar.

A cautious way to use the numbers

Our advice Treat table and depth as clues, not verdicts. If two round brilliants have the same cut grade, compare them in video and choose the one that looks livelier. If a seller quotes ideal numbers without a cut grade, ask which laboratory graded the stone. For fancy shapes, look at how the seller photographs the stone under different lights.

Our advice Treat the numbers as a screen, not a verdict. If two stones have similar figures, compare them in person or in video under the same light before you decide.

Uncertain We did not verify any ideal table or depth percentages, and we do not know how they relate to sparkle for lab-grown stones in particular.

Related reading: What does fluorescence mean on a lab-grown diamond report? · Round vs Oval Diamonds: Sparkle, Size and Price

Sources

• GIA 4Cs, Diamond cut

Fact = stated by the cited source. Our advice = editorial recommendation. Uncertain / it depends = limits of what can be said in general.