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Applying heat to sapphires


#1

I have been retipping sapphires for a number of years and have
not had any trouble. While soldering hinge pins on a bezel set
bracelet using medium gold solder, I discovered that one of the
9 stones (4 mm) had some internal fracturing that I am sure was
not there when I started. Has anyone experienced this
phenomenon? If so, please let me Know how to avoid further
costly problems.Thank You JM


#2

We never heat any stones anymore, except diamonds that have been
thoroughly checked. I know (from past threads) that you will
hear a lot of people tell you not to worry about heating
sapphires but with all the new treatments in the market place
today, you never know what has already been done to a stone that
might effect it in the future when you heat it. Breaks, or
extensions in breaks in the crystal structure can definately
happen with the high heat a jeweler’s torch uses.

Daniel R. Spirer, GG
Spirer Somes Jewelers
1794 Massachusetts Ave
Cambridge, MA 02140
617-491-6000


#3

Bad news, JM. My personal feeling at this point in our gem
treatment evolution is that you should never heat on a sapphire
you can’t readily replace. I replaced several before I arrived
at this unfortunate conclusion. Lately I’ve had several high
grade sapphires and rubies show up with slight girdle chips and
facet abrasions that were most certainly not there upon setting,
and were set with the utmost care. I’m not a gemologist, but a
halfway decent goldsmith who’s set a ton of stones and work
primarily in 18k/plat original designs. I’ve been doing this a
heck of a long time now, and truly feel that today’s stones are
far more fragile than those of yore, and I use a long trusted gem
supplier. My guess is that they’ve been over heat treated to the
point of extreme fragility, but I’ll leave it to our resident
gemologists and cutters to speculate as to why (Mark Liccini,
Alan Beck???). In the meantime, I personally utilize extreme
caution on every stone…and I’m not all that smart (grin).
Mike.


#4

I had the same problem about 4 years ago. After 20 years of
repair work with no problem. It seems a very large number of the
sapphires on todays market are heat treated and will lose their
color if heated. Now I treat all sapphire repairs as if they were
treated stones. Suggest you do the same. Frank


#5

Yes. It’s happened to me. And it was a pretty expensive stone
too. I’ve also seen them etched by boron containing fluxes,
likewise rubies. It’s quite possible to fracture a saphire with
heating, especially if it has gas filled inclusions. This topic
was covered very nicely, I believe, not too long ago. Can’t
remember when, but a keyword search should find it in the Orchid
archives.


#6

I’m tending to agree with you, based on my own experience. And
now there’s Hmong-Su ruby, full of what’s basically glass. I’m
not a gemologist either, but I don’t trust heating ruby now
either.