Dear All- I would really appreciate some help and ideas about
repairing a 'ring of stones." Here’s the story: About 7 or 8 years
ago, I made a ring for a good friend that consisted of 10 lab grown
star sapphires set in Fine Silver. The stones were 6 mm, and were
set in individual bezels that formed a complete ring. This type if
ring is difficult to size. To make it smaller, a complete setting
has to be removed and in this case that would have been too much.
So it was always a little too big, and I tried to compensate for
that by inserting an inner ring to take up some of the space. This
kind of ring should also not be worn all the time, while doing
everyday tasks!
However, the ring has broken into two parts–one segment of two
stones, and the rest in another. So I guess my first question
is-Can the lab grown stones handle the heat of resoldering them to
the rest of the ring? There is only about 3 mm space between the
bezels.
If I did want to remove one setting to make it smaller, would it be
possible to close the circle somewhat without breaking other parts
or stretching the bezels completely out of shape?
Are there any outside-the-box solutions?
Thank you, Thank you!
Sandra Buchholz
elegantbee@aol.com
Hello Sandra:
According to my GIA gem ref. guide Star sapphire shouldn’t be heated
above 1600C and rapidly cooled as it may change the color
permanently. If it is an oiled stone, it shouldn’t be heated at all.
I cracked a blue star sapphire with my torch 7 years ago and it has
made me wonder about the safety of heating them so I don’t. Best you
find someone with a laser welder to do the repair.
Michael R. Mathews Sr.
Sandra,
Now that’s the sort of thing that adds spice to an otherwise
ordinary day! I always look at the sort of situation you describe
from the standpoint that " the piece is essentially worthless as it
is, so why not give it a bloody go eh?" The stones SHOULD withstand
the heat. If you succeed in completing the circle again, having
removed one of the settings, if you are really gentle when you round
it up on the mandrel, checking for loosening stones as you do, you
might just pull it of! There will probably be some loosening, but
you should be able to tighten it as it occurs. In any event, if the
whole job collapses, you haven’t lost anything. When I have offered
a customer with this sort of solution, I have yet to have one
refuse. 
Jerry in Kodiak
Hi Sandra;
Can the lab grown stones handle the heat of resoldering them
to the rest of the ring?
Yes, I’ve done this many times. If you are talking about those star
saphires the used to be made by Linde, they have a script letter “L”
etched in the bottom. You can get those sucker’s glowing, and
they’ll change color, but they return to their original color when
the cool down. They’re cheap anyway.
If I did want to remove one setting to make it smaller, would
it be possible to close the circle somewhat without breaking other
parts or stretching the bezels completely out of shape?
Couldn’t tell you for sure without seeing the design, but if the
bezels are heavy enough, the geometry of what you are describing
sounds like it should be feasible.
Are there any outside-the-box solutions?
As for out-of- the-box, let me out-of-this-cage and we’ll see what I
can do. 
Seriously, if you’ve got a JPG of the ring you can email
me, I’ll be glad to rack my brain for a bit on the situation. I’ve
gotten pretty slick in my old age.
David L. Huffman
According to my GIA gem ref. guide Star sapphire shouldn't be
heated above 1600C and rapidly cooled as it may change the color
permanently.
Mike, you might also point out that 1600C is over 2900F. That is a
bright white heat.
Also, you might note that a corundum that cracks under heat was
likely a completely untreated stone. The GIA asserts that over 90%
of the corundum that is on the market has at least been heat
treated. Untreated stones are a little/lot more valuable that the
treated ones.
Lastly, my own experience with synthetic stars is that they will
accept more abuse that any other. That includes heat and physical
shock. Quenching is still a no-no as they don’t conduct heat well
enough to contract at a uniform enough rate.