Round Diamond Comparison – Depth Lower than Table %

Hi Paul,

I came across these 2 diamonds on James Allen and was stumped by what I saw in the Idealscope images.

– jamesallen.com/diamonds/G-SI1-Ideal-Cut-Round-Diamond-1500331.asp
– jamesallen.com/diamonds/I-VS2-Ideal-Cut-Round-Diamond-1493120.asp

( Update: These 2 diamonds had been sold and removed from JA’s listing. )

First of all, I want to mention that I had read through your entire site on choosing a diamond. Great stuff. Good information. However, this particular phenomenon was not covered in your articles. Perhaps you did and I couldn’t find it. If that’s the case, could you point me in the correct URL.

Here’s my question: Why is the Idealscope image for the G SI1 diamond so weird looking? It has alot more blacks than the usual Hearts and Arrows I had seen on your website.

g color heavily contrasted diamond

By comparison, I picked out an I VS2 and now, the idealscope image looks ‘normal’ to me.

Normal Looking True Hearts

Could you shed light on this? And theoretically, which diamond would be a better choice if I were to pick one?

Thanks,
Jon


Hi Jon,

Thanks for your question. I think you have a very observant eye. Not many people would have observed this when looking at diamond details. From the Idealscope, both diamonds are showing excellent optics with tons of reds and minimal whites.

For the G colored diamond, we see alot more areas of black which relates to more contrast in the diamond. This phenomenon occurs when the diamond has a depth % that is less than the table %. In this particular diamond, the depth is 58.4% and the table is 61.0%. Technically speaking, the difference is really due to diamond with lower crown angles (< 34.0) and some effects of painting on the girdle.

For the I colored diamond, the depth % is higher than the table %. This results in the kind of Idealscope images you will see in the reference chart for light performance.

Hope this helps,
Paul


Hi Paul,

Jon here again. Thanks for the super fast reply. I really appreciate it. Since the G colored diamond has more contrast, will this impact the brilliance of the stone?

If you were given a choice between these 2 diamonds, which would you pick and why?

Jon.


Dear Jon,

While it is true that the G colored diamond will be more contrasted than the I colored diamond, I believe that when both diamonds are placed side by side to each other, the difference in contrast will NOT be easy to detect. To the untrained eye, these 2 diamonds will appear very similar to each other.

However, to the trained eye, you can probably pick up better scintillation from the G colored diamond. That is caused by the additional black areas you see in the idealscope image. However, there is a tradeoff here. The fire and dispersion of this diamond might not be as high as that of the I colored stone.

Assuming that I would have to make a choice between these 2 diamonds, I would go for the G colored diamond. In terms of face up size, the physical measurements are very close to what the I colored diamond offers. Also, there is only a price difference of about $150 between these 2 diamond. However, the G colored diamond is 2 grades better in color than the I colored stone.

This means that the G colored diamond will appear relatively whiter. To me, this is what most people would be able to observe when looking at your ring. The slightly higher price of $150 is definitely justifiable for a 2 grade color jump.

Hope this helps,
Paul

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