I was resizing a stock ring yesterday, after it had been sold. It
was a platinum knife-edge diamond solitaire, and one of the
shoulders snapped off while I was reshaping it. I was on my own in
the workshop, and I only had one hour before the customer was
collecting. That meant I had to made a decision - risk damaging the
stone, or risk losing the sale.
The knife-edge shoulder needed soldering directly onto the collet. I
used an oxy-propane torch, carefully coated the diamond with flux,
and heated it up to soldering temp.
Result: one soldered platinum ring, diamond intact, no loss of
clarity…etc. It was scary, definately, because the diamond went the
same bright red colour as the platinum, but it worked out OK. If it
hadn’t I would have been in serious trouble with my dad.
I think it all depends on the quality of the diamonds - I was
working on an E/VVS, but if it had been a low clarity stone, perhaps
it would have been more likely to break due to inclusions of other
forms of carbon that are less stable. As someone (Leonid?) said,
fracture filled diamonds would probably go black at those kind of
temps, but a fracture filled stone isn’t a real diamond, in my mind.
In the video Charles linked to, the stones were of a very low grade,
chosen for size and cost rather than appearance. I expect a
chemically and mathematically perfect diamond would fare differently
(if such a stone exists), particularly in a low-oxygen environment.
I’m not a fan of rings cast with the stones in, but does anyone here
know if they can be done with platinum? If so, are they cast in an
oxygen-free environment?