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How to evaluate Diamond propertly? ASet & Idealscope

mednat

Rough_Rock
Joined
May 10, 2016
Messages
17
I've read quite a bit at this point, and I still feel like I have so much more to learn. I have requested Ideal scope and ASET images for a diamond and the vendor was able to send them over. Now I've read quite a few tutorials on how to read these, but I'm not sure if my evaluation is correct. I'm having a hard time trusting my first ever evaluation enough to move forward with a purchase or non-purchase. To me, the idealscope looks like it has a lot of leakage (light pink?), that's about as well as I'm able to use these images currently.

Any help would be GREATLY appreciated! I'm feeling pretty lost! :wall:

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Gypsy

Super_Ideal_Rock
Joined
Aug 8, 2005
Messages
40,198
What are the stats on the ring. Carat, table, depth, crown and pavilion angle, color, and clarity.
 

Gypsy

Super_Ideal_Rock
Joined
Aug 8, 2005
Messages
40,198
Crown angle is too low.

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='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: 40.6-40.9 (there is a little give on this). And the crown and pavilion angles must be complimentary which is what the HCA checks for you.
 

mednat

Rough_Rock
Joined
May 10, 2016
Messages
17
Gypsy,

Thank you for your quick response. I've read through the links you've posted, but I'm afraid I'm having trouble understanding still.

Are you saying the crown angle is too low and restricting light coming in? How can you tell that on the ASET/Idealscope, or is that a calculation you're using?

Is my concern about light pink vs dark red valid, or meaningful?

Thanks so much for your help!
 

Gypsy

Super_Ideal_Rock
Joined
Aug 8, 2005
Messages
40,198
Problem with low crown angle is that A) they generally exhibit less fire and B) can be chipping risks depending on girdle and C) they are flat looking stones from the profile and D) can exhibit obstruction. So we recommend crown angles over 33.5 minimum for rings. For a pendant stone, that one is a beauty.

The ASET and idealscope are both okay, so it's not a high risk stone and I don't see any real obstruction. The pink is just photography set up.

It's a different look. There are exceptions to every rule. This stone has a nice tiny table, so if the price is right it may be worth seeing in person and see what you think.
 

mednat

Rough_Rock
Joined
May 10, 2016
Messages
17
Thanks for the explanation! I ordered for a wire price of $7788 (i used cc price for security) it with the ability to return within 30 days, so I look forward to seeing it. It's really tough to understand all of this without actually seeing stones! I went to a couple of local stores, but the level of full court sales that occurred before I could even see a stone was exhausting.

She definitely likes the fire side of diamonds so I'll likely keep looking. Thanks so much for your help!
 
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