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Soldering colored stones

Hi Linda,

I do repair for a living and would offer my 2 cents on this.
Corundum will take heat so all you should have to do is dip it in
your boric/alch. mix and solder on the post with a fast action.
Be sure not to get any flux on the sapphire bacause it will
permanently etch the surface of the stone. good luck Patty in

As an gemologist/appraiser, it is sometimes important to value
as to whether a sapphire or ruby is heat treated. I.e. An
older piece with a high quality ruby that is not heat treated
has a much higher value in the market. The same can be true
with certain older sapphires (Kashmir origin). If you do the
repairs in place that have been discussed some of the albite,
dolomite, pyrite, pyrrholite (and other) solid or liquid
inclusions, which expand with high temperatures, “burst” the
body of the host crystal, forming what is refferd to as a
tension halo. If I as an appraiser see these “halos” in the
sapphire or ruby (They look like a lily pad expanding out from
an inclusion), I value them as heat treated sapphire and ruby
(Which in fact they now are). I would caution anyone who does
this to be careful that they only heat stones that are already
heat treated, or they could cause a loss in value of a
significant stone. Al Gilbertson

Hi Boni, We work on a lot of corundum and I would no longer heat
any stone that has any value. All gem materials on the market
today are being treated in all kinds of ways and you have no idea
of what might happen unless you are thoroughly checking every
piece you work with. We have seen dyed corundum that the dye
leaches out of when you heat it. The heat treatment many
sapphires are experiencing now often seems to leave them much
less amenable to more heat. A lot of the healing fractures
forming in the stones seem to explode upon reheating. If you
don’t mind the occasional law suit from a customer go ahead and
keep heating those stones but I won’t let my repair man heat
anything other than diamonds and even those we check thoroughly
for fracture filling.