Casting diamonds with inclusions in place

I am make jewelry with the lost wax casting method. I have
cast-in-place Rubies and Sapphires with good results, and am now
wanting to branch out and use Diamonds as well. I’m wanting to know
what to look for in a Diamond so that the heat will not damage
it…can it have some tiny inclusions? What about small carbon

Also, I would like to use some “cognac” colored Diamonds, and even
black ones, and/or rough ones. I just don’t want the Diamonds to
crack/crumble! Thank you so much for any you can share.

Peace, Susan Owen Studio Metalsmith

Susan, I’m familiar but not experienced with casting in place. I have
soldered on some thousands of diamonds, though. Generally speaking,
in heating diamonds if anything is going to go it’s not the
inclusions, it’s the cleavages that will get you. And I was always
told not to heat colored diamonds because in some cases the color is
related to heat - that may or may not be actually true, but we just
never did it because it’s an expensive experiment. I don’t think
black diamonds would be a problem - just a gut feeling. Hopefully
someone with cast in place experience will get back to you, too.

Hi Susan

I have had a one time experience with diamond. It was in a Precious
Metal Clay item - a bar of 3 diamonds, temp 1110 for 30 minutes.
Beware!!! There were no diamonds after the firing. IT IS CARBON.
Would be interesting to hear if there were successes/failures.

Rose Marie Christison

temp 1110 for 30 minutes. Beware! There were no diamonds after the
firing. IT IS CARBON 

I’ve torched diamonds up to pretty dam hot and although they
discolored or frosted they didn’t burn away. Perhaps something else
happened to them? Kiln gnomes maybe?

I have no experience with clay but could they have somehow migrated
into the clay during firing?