Do Sapphires have different degree's of density?

[digdeep]

I was reading about green and blue/green sapphires online and came across this comment on higher density on AJ's-- the first paragraph.

https://www.ajsgem.com/gemstone-information/green-blue-green-sapphire-42.html

I have never heard this before, but then I haven't had access to some of the gem books or GIA training that others have. Is this true that green and blue green sapphires are more dense than other colors? Or is it really a non issue because the difference in density is so small? That's what would make the most sense to me............but this is a new subject. Any faceter's that might speak to this density issue?

 

[Bron357]

Hi, firstly AJS gems is making a “wild assertion”, even by their own, other, site information. Green sapphire isn’t the 2nd most dense gemstone.
Density is specific gravity or the expression of “weight compared to size” - a range of say 6mm same size round cut gems will have different “carat weight” according to their density or specific gravity. Higher density equals higher carat weight.
Sapphire is one of the denser gems, but not the second most dense.
I think what AJS gems is trying to point out is that the presence of extra iron molecules in corundum that lead to the green color in green sapphires makes for a relatively higher carat weight ie if a 6mm blue sapphire is put up against a 6mm green sapphire, the green sapphire will have a higher carat weight.
Density is not related to “hardness” or “better impact resistance” it just means that if you have a 1 carat diamond alongside a 1 carat sapphire, the sapphire being more dense, will be smaller in actual size.
This matters if you are say replacing a 6mm diamond in a setting with a sapphire, you will be needing a sapphire closer to 1.25 carats to get the same 1 carat diamond size.

 

[digdeep]

Thanks Bron........well explained!