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Diameter Measurements

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cmcwill

Shiny_Rock
Joined
Feb 25, 2004
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Hi,
I have been hearing a lot about stones whose ''diameter'' is lower than the ''normal'' diameter for a particular carat weight, making them look smaller. What are the normal diameters for .8, .85, .9 .95, 1.0? Does shape factor in at all?

Thanks!
Colleen
 
Shape factors in hugely.




Rounds are going to be much different than a square or marquis etc.




Which are you looking for?
 
Personally I'm looking at Radiants. Is there a website that summarizes this up in a table or something? Where does everyone get their normal diameter mm?

Thanks!
 
Also, I know that a too deep diamond gives the effect that the stone is smaller...is this what leads to a smaller diameter/carat weight? or are the two mutually exclusive?

Thanks!
 
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On 3/4/2004 9:53:17 AM cmcwill wrote:

Also, I know that a too deep diamond gives the effect that the stone is smaller...is this what leads to a smaller diameter/carat weight? or are the two mutually exclusive?

Thanks!----------------



Right... the deeper the cut, the smaller the diameter for the same weight. And deeper cuts are not necassarily better than smaller ones. Cutting deep stones is often a way for the cutter to obtain the haviest cut stone from the rough - and since prince is quoted per carat... you may imagine where this leads.

There are some tables with industry standards for different cuts. Did you see THESE ? It is important however to read the rules (top of page) and the explanation of what these tables stand for (HERE) before using them for anything.
 
Coleen, hate to tell you but you have chosen the fogetten cousin of diamonds for your engagement ring. Not too many people have objectively studied the Radiant for it's diameter and ratios, it's angles and percentages. It came about by a man who wanted a square stone (like an Old miner or cushion cut) but with the brilliancy of a round stone.




Henry Grossbard created the Radiant which he patented his numbers and cut. the market liked the idea, and soon cutters created styles similar to his, but each variation was different. Different angles, different cuts on the crown and pavillion...Some were flat like princess cuts in the crown, and some were as high as Asschers. Most radiants are rectangular, especially in the larger sizes, as this I believe, was the original type that sold the most. People wanted rectangular stones like emeralds, but with sparkle. The really square stones gained popularity after Lucida, and are slowly growing in popularity again. Hnece princess being the second most popular after the RB.




Now the AGA charts accounted for radiants as emeralds, because they tend to have similarities in crown height and depth percents. Radiants ARE NOT princess cuts with no corners. Their pavillion patterns are NOT the same, and their crown heights and cuts are different. Aside from the help I got here, I have never found a real comprehensive list of radiant features and tests to run a radiant under like a HCA for round stones...shaped stones are too unsymetrical to get perfect measurements. But yes, there are better angles and better percents.




Depth and table should be under 70%, (I personally prefer them to hang around 65%, with depth being slightly 1-3%s over table) Girdle should be thin to medium, maybe slightly thick., it should NOT have a FLAT crown like a princess or the depth of one, and the pavillion pattern should look more like a RB, but square, and the crown should have one step cut like an emerald, and then on the inside of that step cut should be cut with about 16 or so facets, somewhat like an RB.




You do have to see the stones, and it's much harder to rely on numbers alone with these, because the crown height should be directly proportional to the pavillion depth, to get that magical ratio where the reflection and refreaction is just right. There are so many cuts, and so many angles that no one has standardized the cut, much less determined optimal numbers on the generics. In my opinion, Grossbard has come the closest, because this has been his invention, and he put in the most research into it. Someone may in the future, but as of now, it's best to SEE it. And when looking for a good table, get under 70%, but have table be slightly smaller than the depth and that should be more brilliant, from the ones I have seen... Good luck!
 
Thanks everyone!
Valeria I have seen those charts and am using them profusely to measure the cut grade of whatever stone I buy. I just didn't know if I ended up with a 2B stone by cut...but the diameter was smaller....that I would have a smaller looking diamond. Now I know one measurement (diameter) follows another (Depth:Table) and I should stick to the chart.
Nicrez thanks for your unending optimisim! I can't wait to go looking again, one more week till I see the boyfriend! We WILL find the perfect stone.
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And then I will post my top pics and have the PS crowd help sort it out in case I'm missing anything!
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Colleen, I really hope I am not depressing you! It's just the reality of finding a well cut generic radiant is quite difficult and takes a lot of reasearch and legwork on your part to SEE the stones. I just want you to see the reality of finding it won't be as easy as other stones,YET...
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It's a rough process, and like I said I did it EVERY DAY for 3 months until we found ours...It became an obsession, and I know it would have been much easier to find a RB, but i just wouldn't have it...(poor guy, huh?)




Colleen, I know yours is out there...It just needs to be surfaced by your search and when you find a few good cuts, it's up to your eyes to see which one really calls you. I wish you all the best, and you better post specs!
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Maybe we can bring Radiants into the Princess cut popularity by all our searching and posting!
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The Crusade continues! I will have a lot more information to post after next Friday when my boyfriend and I take a look at the one he found and head down to Philly. Thanks for all your support and countless advice!
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The measurements for my stone are:
Brilliant cut
5.98 x 5.93 x 3.35 mm
o.71 Cts.
E SI1
Is this a good diamond?
 
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