I don't know your skill level with repairs of this sort, so I'll err
on the safe side . . . forgive me if it seems patronizing in tone. You
shouldn't have any problems with the diamonds as long as you abide
by four conditions.
make sure the diamonds a clean and covered with a boric
never heat them to a visible red color. It won't hurt them to
momentarily get red hot, but if they do, the longer they stay that
way, the greater the risk of burning the surface of the diamond.
allow them to come up to temperature somewhat gradually, and let
them air cool, never quench them.
if the diamonds are heavily included or fractured, the risk is
considerably greater that they'll be damaged by heating. This,
unfortunately, is a judgement call. Let's just say, if it's easy to
see inclusions with the naked eye, it's risky. A few small black
flecks shouldn't be a problem, a white feather might be cause for
Now, your greater problem is previous solder seams. It might be
advisable to use a relatively low temperature hard solder, such as
easy or extra easy. And while you're at it, just to prevent problems
of old solder flowing into areas that you'd rather it didn't, you
might use yellow orchre or water based white out (typewriter
correction fluid), or even rouge dissolved in water, to paint the old
solder seams before you do any work. Take care, if you are applying
liquid flux while the article is warmed, not to splash it on the
diamonds and thereby shock them. Best of luck.
David L. Huffman