1b yellow diamond

[reallyanewbie]

I have read the best yellow diamonds belong to this class. How do you know if the diamond is actually 1b ? who verifies this ?

Also GIA certs on round brilliant colored diamonds, dont give a crown or pavilion angle. Why not ? woudnt the same measurements
that make a brilliant round/ideal cut colorless "white" diamond sparkle, also have a great effect on a colored diamond of the same cut ?
I understand colored diamonds are all about the color, but a round colored diamond with a great ideal cut would be even better ?

 

[kenny]

I have read the best yellow diamonds belong to this class. How do you know if the diamond is actually 1b ? who verifies this ?

Also GIA certs on round brilliant colored diamonds, dont give a crown or pavilion angle. Why not ? woudnt the same measurements
that make a brilliant round/ideal cut colorless "white" diamond sparkle, also have a great effect on a colored diamond of the same cut ?
I understand colored diamonds are all about the color, but a round colored diamond with a great ideal cut would be even better ?

FCDs are cut to maximize the color strength and the weight.
They are not cut for light performance.
That is why GIA does not provide a cut grade or even crown and pavilion angles on either of their two grading reports for FCDs.

I know a bit about FCDs but have not heard of and am also curious about this "1b" thing.
Where did you hear about that?

Here is GIA's scale of their nine FCD color grades.
It is the gold standard for grading of FCDs and does not include any scale/grade that includes terms like 1b.



You asked, "Wouldn't the same measurements that make a brilliant round/ideal cut colorless "white" diamond sparkle, also have a great effect on a colored diamond of the same cut ?"
The answer is, yes and no.
Yes, it would improve the light performance. (actually, neither are many white diamonds)
But, no, better light performance would not improve the strength of the color.
Again, FCDs are cut to make the color stronger because that can earn it a higher color grade from GIA.
This translates to a MUCH higher price moreso than better light performance.

Personally I've bought/sold/traded FCDs to get the best of both worlds, color AND light performance.
Expressing this on PS has made me somewhat of a pariah to FCD vendors because they want to sell every FCD in their safe ... not just the very few that happen to also have good light performance.

 

[reallyanewbie]

Type Ib diamonds absorb green light in addition to blue, and have a more intense or darker yellow or brown colour than Type Ia diamonds. The stones have an intense yellow or occasionally brown tint; the rare canary diamonds belong to this type, which represents only 0.1% of known natural diamonds.

Type 1b
If the nitrogen atoms are evenly spread out throughout the carbon lattice, then the diamond is said to be a Type 1b diamond. These diamonds absorb green light as well as blue light, and have a darker color than type 1a diamonds. Depending on the precise concentration and spread of the nitrogen atoms, these diamonds can appear deep yellow ("canary"), orange, brown or greenish. Less then 0.1% of diamonds belong to Type 1b.
http://24carat.co.uk/frame.php?url=diamondtypes1a1b2a2b.html

Here are two posts, top is from wiki.

Thank you for your reply, I sort of sensed it was going to lead there. It seems like more often then not, buyers of colored diamonds
prefer stronger/best color over any type of light action. Light action would detract from strong color. I have seen some well cut round vivid yellows that in sunlight/light, sparkle beautifully (with the yellow fading out) and in a non lighted/low light situation look an amazing yellow. That is something pretty amazing and appealing to me, but looks like I, we are in the minority, and the mkt caters to the
majority.

 

[kenny]

Ah yes.

I had heard of these types but didn't really think of them in terms of FCDs.

Thanks.