The table is the uppermost, flat surface of a diamond which runs parallel to the plane of the girdle.

The table % of a diamond is calculated by dividing the width of the table facet by the width of the diamond. So, if the table facet is 3 mm across, and the diamond is 4.5 mm wide, its table % is 66.7.

Table % is incorporated in the Cut grade of a diamond. For this reason, when purchasing a diamond, use the Cut grade first (since it balances multiple measurements, not just table %). Once two diamonds of equal cut are being compared, consider table % as a further refinement.

A larger table size equates to less crown height. This means that, carat weights being equal, a diamond with a larger table tends to be a bit shallower and wider, therefore appearing larger to the observer. Diamonds with a very large table may actually be brighter than other diamonds because they return a lot of light through the top of the diamond, but they will also tend to have less fire, since there is less opportunity for the light to be broken into rays of color by the necessarily smaller facets surrounding the larger table.

Learn more about the anatomy of a diamond.