What is Ideal?

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Oct 23, 2002
I'm trying to find the right diamond and have an understanding the at cut is the most important criteria. Looking for an Ideal cut diamond, it is my understanding that the Depth should be 61.5% Table 53-57%, Crown 34.5, Pavillion 43.10% ..... Correct?. I call Tiffany (for example) and state that I'm looking for a diamond that is AGC 000 (Ideal cut). They quote me on a stone that is Table 60%, Depth 60.1% and tell me that that is Ideal. Another Dealer tells me their stone is Table 59% and Depth 61.7 and that that stone is Ideal. I've yet to find a stone that meets the proportins I stated above.

1) Is my understanding for a stone with the most Fire as I state above?
2) AGC 000 = Ideal Cut?
3) Are there many versions of 'Ideal'?
4) All I have is the certificate when I make the decision? How do I know that I'm making the right choice without seeing the stone? (FYI: Once decided, I'll fly to fetch the stone.)

Please advise.



Garry H (Cut Nut)

Aug 15, 2000
You fly there - but what makes you think you will be able to make an expert decsion :)

There are many versions of ideal.
I do not like the AGS version - if you wish to use that approach use the AGA version - Dave Atlas under 'appraisers' (he is an expert you could better use to have 1st look at the stone than your own eyes).

You should read my Tutorial here.

If you can see the stones buy a
if not use the 'cut adviser' link above.

Do not use the pavilion depth (culet changes the info).
Aim for pavilion angles below 41.

Try to enjoy it, but it is a difficult thing to find a well cut diamond.

Finally use the search buy cut quality on the front page.


Oct 26, 2002
I am new to this, but I seem to have learned that Tolkowsky's cut is an important standard for an ideal cut. The others fall into two catagories. 1 - other opinions which can be quite valid. 2- dealers who do not have a real ideal cut, so they created their own definition for no reason other than to increase the number of stones they can charge a lot for. The dealers you spoke to certainly fit into the catagory of telling a 1/2 truth to sell a stone and I would be upset at them for trying to mislead you.


Sep 2, 2002
Hi Paul!

I'd take CutNut's advice and check out some tutorials on the web. The one on pricescope is a great place to start. You'll find that the American Ideal Cut (what AGS, not AGC, uses) actually has ranges for all four criteria that you mentioned (the percentages and angles), so that you will get all sorts of different measurements that fall within the ranges that have been named "ideal".

Again, CutNut's suggestion that the current ideal category needs revision is probably correct...not that my opinion carries half the weight as his. :) Even within the AGS Ideal ranges, there are variations in diamond quality...they aren't huge, but not every AGS Ideal Cut is a "wowza!" rock. Best advice I got in my search process was "Make sure you look at rocks to know what you like!!! NOTHING compares to the eyes!!!" Once you have an idea of what you like, you'll be able to feel more comfortable with a purchase on the web.

As far as brilliance vs. fire, check out the pricescope tutorial. It explains the ranges for the Ideal Cut, and there's a graph that displays where in those ranges you'll end up with firey-er rocks. Hope that helps....have fun!!!:praise:
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