Advice on choosing between two SI1 .90 round I


Apr 20, 2016
Hoping for some advice out there choosing between two stones, both SI1, I, .90, excellent cut.

Stone A I've worked with both a local jeweler and JA. The local jeweler wants to sell me the diamond pictured below along with GIA report



I searched for it online with the GIA #, and Blue Nile does not have it today but they previously did have it in inventory until December 2015, and still have the page and price they listed it for, which is here . He doesn't have it inventory (he used polygon to find it), but could get it shipped in to have me look at, and he spoke with the seller while trying to find an eye clean SI1, and assured me this is eye clean. He wants to sell me it for $450 more than BN had it listed for back in December (I assume combination that he doesn't have the buying power of BN and thus has to pay more for it, and he has to charge a higher margin to cover the brick and mortar overhead...still a good bit more).

Stone B I narrowed in on a stone on JA that is my main alternative: . With a pricing discount, I can get it for just below $3800. GIA report is below



Rings are similar cost and available from both, so I consider that a wash. Just trying to assess if I'm getting a much better deal with the JA stone--ie a better stone for a cheaper price than the other (without having the benefit right now of hi def views of the stone the local jeweler wants to sell me). If all else is equal the local jeweler may make it easier to have someone to take it into, etc. Thanks for any insight or opinions, trying to decide and pull the trigger very soon!


Aug 8, 2005

Round Diamonds 101:

The entire purpose of faceting a diamond is to reflect light.
How well or how poorly a diamond does this determines how beautiful it is.
How well a diamond performs is determined by the angles and cutting. This is why we say cut is king.
No other factor: not color, not clarity has as much of an impact on the appearance of a diamond as its cut. An ideal H will out white a poorly cut F. With round diamonds even a GIA triple Excellent is not enough. And you must stick to GIA and AGS only (HPD in Europe is good as well). EGL is a bad option: [URL=''][/URL]
So how to we ensure that we have the right angles and cutting to get the light performance we want?
Well one method is to start with a GIA Ex, and then apply the HCA to it. YOU DO NOT USE HCA for AGS0 stones generally, though you can. In general, AGS0 trumps HCA though as one examines the actual stone and the other does not.
The HCA is a rejection tool. Not a selection tool. It uses 4 data points to make a rudimentary call on how the diamond may perform.
If the diamond passes then you know that you are in the right zone in terms of angles for light performance. Under 2 is a pass. Under 2.5-2.1 is a maybe. 2.6 and over is a no. No score 2 and under is better than any other.
Is that enough? Not really.

So what you need is a way to check actual light performance of your actual stone.
That's what an idealscope image does.
It shows you how and wear your diamond is reflecting light, how well it is going at it, and where you are losing light return. That is why you won't see us recommending Blue Nile, as they do not provide idealscope images for their diamonds. BGD,BE, James Allen, GOG, HPD, ERD and WF do.

The Idealscope is the 'selection tool'. Not the HCA.
So yes, with a GIA stone you need the idealscope images. Or you can buy an idealscope yourself and take it in to the jeweler you are working with to check the stones yourself. Or if you have a good return policy (full refund minimum 7 days) then you can buy the idealscope, buy the stone, and do it at home.

Now if you want to skip all that... stick to AGS0 stones and then all you have to do is pick color and clarity and you know you have a great performing diamond. Because AGS has already done the checking for you. That's why they trade at a premium. Some AGS0's are better than others though, so pay attention to any ASET or IS provided.

In general with rounds, you will want a table 60% or less. A depth between 59 and 62.4. Crown angle 33.5-35. Pavilion Angle: 40.6-40.8 (there is a little give on this). And the crown and pavilion angles must be complimentary which is what the HCA checks for you.


Apr 20, 2016
Thanks Gypsy, they are both not the best proportioned, though the JA one is closer. I will take up the idea regarding the idealscope after narrowing down

and tyty333, thanks, that one does look like a good option. There are a few other options on JA, but that looks like a good option especially with the color bump up, and I doubt the medium blue fluorescence would be an issue? In addition to that, these also appear viable, if they are eye clean, unless I'm missing something that would disqualify any of these.

They all pass the HCA <2.0....I'll ask about them being eye clean
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