Depth/Table % etc - Princess Cut - confused?!?

[RADIANTMAN]

David - in my experience, which is pretty substantial but limited to radiant cuts, surface area to depth does mean something with respect to performance, but not as a stand alone measure. It is only meaningful as one of many measurements taken together.

The problem with any kind of depth % measurement, no matter how we calculate it, is that too many people think it means something it doesn''t. Most people seem to use it as a measure of spread, and as Paul has repeatedly correctly pointed out, for radiants and princesses, it isn''t a measure of spread. If it means anything, it has to do with performance.

That''s why providing an actual direct measurement of spread is so important. I hope you will start a trend by including it in your reports.

 

[oldminer]

My intention is to produce all fancy reports with visual surface area in mm on the report. It is good simply as a comparision tool for apparent size if one neglects eye trickery possibilities.

Spread is the relationship of width to depth, but we now see the spread and depth does not tell about the bulge or lack of bulge in the pavilion. The bulge has a huge effect on the weight of the diamond and the depth % does not necessarily show what is taking place. I believe that when we look at accumulated data, we will find that depth percentage sometimes relates to performance and on other occasions does not relate well at all. The bulge is not being accounted for.

In the overall, the old style physical measures and percentages mean very little in the new world of diamond grading by direct measure. As a legacy we will continue to give them regardless of importance and as a comforting factor to traditional sellers. In truth, girdle thickness, crown angle, polish, symmetry and possibly some spread measure % are all of any real importance to the final outcome so long as light performance is measured digitally.