emerald cut shopping

[schmancy]

I have been reading up on the 4 c’s, and on emerald cuts in particular. The new AGA emerald cut chart has been very useful, but I have a couple questions about cut grading. First, why is crown height the one criteria shown in the chart which is virtually never identified in on-line diamond searches? Typically I find table, depth, polish, symmetry, and girdle when I search for stones. Second, how does the culet contribute to the quality of the cut? On bluenile.com, which seems to me more marketing oriented (and perhaps less objective?) than some other sites, a small culet is considered beneficial to the emerald cut, but they give no info as to where their emerald cut grades come from. Any more detailed info on the selection of emerald cuts would be welcome—I have read through everything I could find on the pricescope site.
Thanks

 

[pricescope]

You're right most of the grading reports don't show crown and pavilion angles even for round diamonds. You can obtain this information using Sarin or Ogi measurements.

During the manufacturing process, the culet is often polished as a flat facet so that it does not get chipped as the other facets are polished. Ideally, the cutter ‘closes’ this facet to a point, but sometimes it remains as a small extra facet which is not all that bad because it protects the culet from chipping as the diamond is handled and while the jeweler is setting the stone.

A diamond behaves as a window if opposing facets are parallel, and this is exactly what happens if the culet is too big. You see straight out the hole in the bottom. If you have ever seen a large old cut diamond you probably know what we mean.

The culet size is listed on a cert and your diamond’s culet should be pointed (no culet), very small, small or medium because these are not visible to the naked eye.

Large to extremely large culets may be visible to the naked eye and can be treated almost as though they are inclusions.

This applies for emerald as well.

 

[oldminer]

If one limited the postings to diamonds which had crown heights listed, there would be very few diamonds found in any search engine, including Pricescope. It is that way do to tremendous resistance of the trade to adopt more open information availability and the contention that more data does not really help anyone.

Obviously, I believe more data would benefit you and many others. In time, there will be more information and better ways to find diamonds that are well crafted. Right now, it is difficult. There are some savvy vendors who have found sources for well cut fancy shapes. They are doing nicely with these stones, too.

 

[schmancy]

Thanks for the feedback--both responses are very helpful.