Total Depth, should I be concerned

[tinhtu]

Is this answer for the question below true? I saw a lot of H&A on WF and GOG stones have the table depths more than 61% and have excellent light return. I am confused and need help. Thanks


Q Thank you in advance for your feedback. I think you have an excellent site. Here is the specs on a diamond I''m considering and I would like your feedback on the Total dept. This info is from a AGSL report: Cut:000 Table: 56% Crown Angle: 34.6 Pavilion Angle: 40.9 CR. %: 15.3 Pav % 43.2 Total depth: 62.2 size: 6.56-6.59 x 4.08mm color F Clarity SI2 All the other measurements and angles seem to be almost perfect so how can the Total depth be so far from ideal? Is there an error on the report? Thanks Dan

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A Hi DanB, Errors? Labs make plenty of mistakes. But it appears that this stones depth is too deep. With a total depth percentage exceeding 61%, the stone becomes a class IV and would only return a maximum of 32%-38% of the light that enters the stone compared to a well proportioned diamond at 88%-91%. Remember additional weight on the pavilion of the diamond equals more money in their pockets.

 

[aljdewey]

Date: 11/9/2005 12:34:11 AM
Author:tinhtu



Is this answer for the question below true? I saw a lot of H&A on WF and GOG stones have the table depths more than 61% and have excellent light return. I am confused and need help. Thanks


Q Thank you in advance for your feedback. I think you have an excellent site. Here is the specs on a diamond I'm considering and I would like your feedback on the Total dept. This info is from a AGSL report: Cut:000 Table: 56% Crown Angle: 34.6 Pavilion Angle: 40.9 CR. %: 15.3 Pav % 43.2 Total depth: 62.2 size: 6.56-6.59 x 4.08mm color F Clarity SI2 All the other measurements and angles seem to be almost perfect so how can the Total depth be so far from ideal? Is there an error on the report? Thanks Dan




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A Hi DanB, Errors? Labs make plenty of mistakes. But it appears that this stones depth is too deep. With a total depth percentage exceeding 61%, the stone becomes a class IV and would only return a maximum of 32%-38% of the light that enters the stone compared to a well proportioned diamond at 88%-91%. Remember additional weight on the pavilion of the diamond equals more money in their pockets.

I don't know who gave you that information, but that someone is reaching a bit.....and embellishing to boot.

Most folks prefer a stone with a lower depth......but it's a PREFERENCE. If a stone leans toward the deeper side, it does carry some of its weight in the pavilion, and that means it has some marginal affect on total diameter (size - what you see).

62.2 is on the fringe.....but it's still in the ballpark. There are a lot of changes going on at the major labs regarding their proportions, but I still think today that Dave Atlas' cut grades make a pretty good starting point. You can find them here: http://www.gemappraisers.com/

On the left navigation bar, click on "Old AGA cut Grading charts & rules", then select "round" from the drop down bar on the right. You'll see that the 1A grade allows for diamonds with up to 62.3 depth.

Again, there may be a visual difference if you were to select a diamond with a depth more in the proverbial "sweet spot".....but I don't think the diamond you've mentioned should be dead, either. If you're really concerned, I'd suggest going to an independent appraiser and getting his opinion on it.

Hope this helps ease your concerns.

 

[JohnQuixote]

I prefer an upper limit of 62.0 for goods larger than melee, but diamonds close to that can still be dynamite, depending on the other parameters.

With those combos 62.2 indicates a slightly thick girdle, but could be a very good performer. I did those measurements with single ray trace at 62.2 (1.08 ct) and 60.8 (1.04 ct, thinner girdle).

 

[JohnQuixote]

60.8 depth

 

[valeria101]

Date: 11/9/2005 12:34:11 AM
Author:tinhtu

With a total depth percentage exceeding 61%, the stone becomes a class IV and would only return a maximum of 32%-38% of the light that enters the stone compared to a well proportioned diamond at 88%-91%.

These numbers seem total fantasy. It would help to know what the % were taken of, and how these things are modeled etc.

By all accounts, depth alone says squat about light return - so this evaluation flies in the face of every cut quality evaluation for round brilliant diamonds starting with Tolkowsky and ending with the latest GIA and AGS cut grading studies.

If this guy is right, everyone else on the planet is wrong

OK, I have to admit that the 1% of extra depth add a bit a weight - more if it is due to a wider girdle than other details. However, the difference is easy to observe in diameter size that is apparent on the lab reports and prices are out there to see too. It doesn''t seem to matter, really. If you were asking about a 65% deep round, that would deserve some ink, this... well, not quite.

Just my 0.2, of course