The table is the uppermost, flat surface of a diamond, and runs parallel to the plane of the girdle.
The table percentage of a diamond is calculated by dividing the width of the diamond. For example, if the table facet is 3 millimeters across and the diamond is 4.5 millimeters wide, its table percentage is 66.7 millimeters.
Table percentage is incorporated in the cut grade of a diamond. For this reason, when purchasing a diamond, use the cut grade first. Once two diamonds of equal cut are being compared, consider table percentage as a further refinement.
A larger table size equates to less crown height. This means 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 allow more light into the stone, 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.