Teach Me!

[lulu_ma]

Yes and NO! Depending on cut quality - the shorter the ray paths through a diamond the less color will be seem face up.
Perfect rounds have very short ray paths, averaging around 2.5 time diameter.
Diamonds cut to increase color have three time avg ray path lengths.
Most fancy shapes have poor light return and so they show lower colors.
The round and cushion shown are digital and have identical material color!

I’m going to piggy back off SH’s question-why did so many old cut diamonds have face ups whiter than grade?

I’d love to know the science behind this phenomena.

 

[Garry H (Cut Nut)]

I’m going to piggy back off SH’s question-why did so many old cut diamonds have face ups whiter than grade?

I’d love to know the science behind this phenomena.

Did you see my post before yours?
That is why - less than perfect light return.

 

[lulu_ma]

Did you see my post before yours?
That is why - less than perfect light return.

I'll admit that I am confused. Super Ideal diamonds seem to face up whiter due to excellent light return. Conversely, OECs and OMCs face up whiter due to poor light return and/or short ray paths?

 

[Garry H (Cut Nut)]

I'll admit that I am confused. Super Ideal diamonds seem to face up whiter due to excellent light return. Conversely, OECs and OMCs face up whiter due to poor light return and/or short ray paths?

Sorry - I misread your post.
Old cuts that face up whiter are often from South Africa - the cape yellowish - many of which are blue fluorescent. That improves the colour you see in good lighting.
But the issue is complex. The models in this image are the same diameter and color absorption because they are virtual software modeled diamonds.

 

[lulu_ma]

Thanks for the info.

Interestingly, I was recently at Shimansky in Cape Town and tried on these two. The round is a GIA M color with faint fluoro. The oval is a IGI J color.

In person the face up color looked quite similar:

 

[Karl_K]

Smaller tables and no lower girdle facets under the table means there are fewer small virtual facets that concentrate color.
Less of a difference than crushed ice to rb but it is there.

 

[snaphappy]

Thanks for the info.

Interestingly, I was recently at Shimansky in Cape Town and tried on these two. The round is a GIA M color with faint fluoro. The oval is a IGI J color.

In person the face up color looked quite similar:

I think that's why they were just called cape diamonds in the old days. They're all quite similar to the naked eye.

Cape Town? Wow!! Have you been to the museum, is it in Kimberly? I'd kill to see the Eureka Diamond!!

 

[Garry H (Cut Nut)]

Thanks for the info.

Interestingly, I was recently at Shimansky in Cape Town and tried on these two. The round is a GIA M color with faint fluoro. The oval is a IGI J color.

In person the face up color looked quite similar:

IGI tends to be softer on colour so the difference should be slight anyway. But to see colours diffused light works best

 

[lulu_ma]

I think that's why they were just called cape diamonds in the old days. They're all quite similar to the naked eye.

Cape Town? Wow!! Have you been to the museum, is it in Kimberly? I'd kill to see the Eureka Diamond!!

I did go to the Diamond Museum in Cape Town. Unfortunately, the Kimberly mine was a 12 hour drive so I did not see the famed diamond!