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Grading A Diamond's Table 
The table is the upper flat facet of a stone. The size of the table determines
the look of the stone: the bigger the table, the greater the brilliance
(the sparkle) and the less the fire (the variety and intensity of the color
reflected/refracted); the smaller the table, the greater the fire and smaller
the brilliance. (It's more wasteful to cut rough diamonds to have smaller
tables, thus diamonds with smaller tables are better.) I like to see tables
from 56-60% as my default standard, with closer to the center of that formula
the better. Diamonds aren't magic, they are natural prisms and wonderful
things when cut well, but conversely a stone with a 65% table is seriously
effecting the diamond and these "skating rink" tables are to be simply avoided...
Tolkowsky's
recommended cut height for a Round Brilliant is 59% that of the diameter
of the diamond, which breaks down to about 43% for the pavilion, and 16%
for the height of the crown. This 59% is probably the most crucial dimension
of the stone. For easy reference just remember 60/60 for the depth and
table, knowing that the optics are effected seriously when out of range
for a beautiful diamond...
You might find diamonds that are too shallow (the height is significantly smaller than 58.5%) or too chunky (significantly over 61%). Don't buy any stones that deviate too much from this value. You will sometimes see other standards, like the Eppler and Scandinavian Cuts, that look just like the Tolkowsky Cut, but the height is at 58%. I call the really deep stones "Stove-piped", which wastes the diameter for the excess column of mass from table to culet. Avoid boneheaded cuts and you'll be better off, remember that since diamonds are seriously discounted with poor math the cheapest stone you find might well be the screwiest... Don't just ask for color and clarity, it's asking for trouble!!!!!
| Table proportions | AGS cut grade |
|---|---|
| 46.3% and smaller | AGS (10) |
| 46.4% to 47.3% | AGS (9) |
| 47.4% to 48.3% | AGS (8) |
| 48.4% to 49.3% | AGS (7) |
| 49.4% to 50.3% | AGS (5) |
| 50.4% to 51.3% | AGS (3) |
| 51.4% to 52.3% | AGS (1) |
| 52.4% to 57.5% | AGS (0) |
| 57.6% to 59.5% | AGS (1) |
| 59.6% to 61.5% | AGS (2) |
| 61.6% to 63.5% | AGS (3) |
| 63.6% to 65.5% | AGS (4) |
Judging The Table
If you look at the crown (ignore the kite and upper girdle facets), you'll
notice that the star facets and the table make a design that looks like
two staggered squares. Make sure that these do indeed look like squares.
The squares' lines should be straight, or better yet, "bowed in", as the
Tolkowsky Cut guidelines call for.
If these squares look bowed out, then you have a large table. Buy a diamond
that does not have the table bowed out. You want to target tables from
56-60% to be in a most pleasing range... Remember that most diamonds are
a compromise, but don't be too fast here to tolerate a table over 64%
to get yer price down, the optical properties of the diamond are seriously
effected by tables over 64%, and thus are heavily discounted in this range.
I'd rather see the table in a round diamond at the 59% mark if possible,
think of this as the center of a range, and the place where you can really
fine beauty.
I love to announce my "Golden Rule" about now for the average consumer, and that is the rule that I call the 60/60 rule... If you keep the depth and table at approximately 60% for each catagory you have the basic criteria for a brilliant and beautyiful diamond... Never let anyone just give you the color and clarity again, these are minor players in the initial stages of determining a diamond's beauty, after you've determined the cut you are ready to consider the other catagories, but now before you access the cut and optical potential of the stone.
