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HELP, which 1.5 is a better stone?

kcamp

Rough_Rock
Joined
Apr 7, 2016
Messages
3
I am looking at 2 diamonds and am trying to decide which is better for the price.

the first is: 1.50 GIA, xxx, H, SI1, cert#1213054988 priced at $11,600

the 2nd is: 1.51 GIA, xxx, H, SI11, cert#6212740664 priced at $10,000

Thanks.
 

cvu

Rough_Rock
Joined
Mar 29, 2016
Messages
11
Hi kcamp. Both diamonds are likely to be rejected by the community here on Pricescope. Their proportions are not falling into ideal cut territory, particularly the pavilion angle is too high on both stones (and not complementary to the crown angle), the second moreso than the first.

Consider using the HCA tool (https://www.pricescope.com/tools/hca) to evaluate stones to consider only ones below a score of 2.0. This helps to narrow down the enormous selection of diamonds out there on the web. From there, you can ask vendors for more information such as images, ASET/Idealscope, etc. to help you get a better idea of if the diamond is truly a top performer. In this price range, most are going to recommend not purchasing sight unseen without these images unless you're very comfortable with the dealer and their return policy.

Many members are happy to make selections of likely top performers if you provide your preferred specifications for color, clarity, size, and budget (and vendor if you have one). Alternatively, the front page of Pricescope has a tool that makes it all too easy to narrow the field on your own with a little bit of reading on this site and forums.
 

Gypsy

Super_Ideal_Rock
Joined
Aug 8, 2005
Messages
40,198
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='https://www.pricescope.com/community/threads/egl-certification-are-any-of-them-ok.142863/']https://www.pricescope.com/community/threads/egl-certification-are-any-of-them-ok.142863/[/URL]
So how to we ensure that we have the right angles and cutting to get the light performance we want?
https://www.pricescope.com/wiki/diamonds/diamond-cut
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.
https://www.pricescope.com/wiki/diamonds/holloway-cut-advisor
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. https://www.pricescope.com/wiki/diamonds/firescope-idealscope
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 (no give on this) which is what the HCA checks for you.
 
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