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Discolored sapphire


#1

I think my 6 by 8 sapphire darkened somewhat after exposure to hot
wax in the process of making a wax pattern does anyone have any
thaughts on this problem or any on a company that treats
colored stones.

Ralph C. Cross
Fremont Jewelers


#2

Hi Ralph; It’s not very likely that such low temperatures would change
the color of a sapphire. True, they are heated after being mined to
distribute the color more evenly throughout the crystal, but that’s
done at much higher temperatures. Perhaps you’ve still got wax on the
stone. Try a little lighter fluid on a soft cloth and rub it down
thoroughly.

David L. Huffman


#3

Ralph, From my limited understanding of Sapphires hot wax comes no
where near the temperatures needed to change the color of a Sapphire.
Now I don’t know about diffusion treated Sapphires.

Doug Frey
www.dfrey.com


#4
I think my 6 by 8 sapphire darkened somewhat after exposure to hot
wax in the process of making a wax pattern 

This is highly unlikely. The very low temperature of the melted wax
will have no effect on a sapphire. It takes temperatures of near
2000C to affect color in a sapphire. It is possible that some of the
dye in the wax has coated the stone. A few hours in a bath of
Acetone should cure that if a quick wipe with it doesn’t

Don Rogers


#5
    I think my 6 by 8 sapphire darkened somewhat after exposure to
hot wax 

Uh,… I don’t know what anyone else is going to say, but… I’ve
heated sapphires to a dull red, and never had any color change either
way. It’s not luck, I’ve had to do this many times, each time no
change. I’ve frosted a few too, but nothing a little repolishing
couldn’t fix. Try putting it in the ultrasonic for awhile. If that
doesn’t work, consult your certified gemologist, have it tested.

Dean D Amick


#6

Ralph, It is hard to imagine darkening your stone from just heating it
with wax.I would try cleaning the stone with some lighter fluid to
dissolve any wax on the stone and then cleaning it in an ultrasonic. J Morley Coyote Ridge


#7

In a related question… and hopefully not a dumb one:

What about ametrine? The change from purple to yellow (or
vice-versa?) can be done with heat. My understanding is that it is a
significantly lower temperature than most gemstone heat treatments.
Anyone know if a spatula pressing the stone into wax is too hot for
this? I have a perfectly “balanced” ametrine and I’m afraid to try it
for fear of shifting the color balance, or ending up with an all
amethyst stone.

Sorry if this question seems redundant…

Dave

Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#8

Dave Sebaste: I can’t answer your question about the posibility of
discoloring your stone with heat but (depending on what type of wax
you are using) I would not expect that a hot spatula would supply
enough heat to sink the stone into the wax.I use a small soldering
iron with a modified tip for this application and as a wax pin.

Regards
Ralph C.


#9

Hi Dave; Don’t do it. In my opinion, the only stones that should be
considered for being heated with a hot wax tool and “melted” into wax
follow the “red, white, and blue” standard which goes as follows.

Red=Ruby
White=Diamond
Blue=Sapphire

The same goes for re-tipping, except beware glass filled (Hmong Su)
rubies, never-before heat treated sapphires (CO2 filled negative
crystals), and badly included diamonds (or those “enhanced” by older
methods of drilling/filling a la Yehuda). Yipes! that’s enough to
make the novice nervous about heating just about anything. . .

David L. Huffman


#10

All, I have heard many people tell me that ametrine is man made. As
far as I know it is not possible to heat treat a part of an amethyst
crystal to become citrine. I have seen several pieces of man made
rough that were being sold as ametrine, but they were not of any
quality. Ametrine is naturally occurring in most deposits of
amethyst. Bolivia is the most prolific producer of natural rough.
Producing thousands of carats annually (maybe more). As far as heat, a
hot spatula applied to a stone should not change the color. The heat
from the spatula may cause the stone to fracture because the heat is
unevely applied. I suggest that instead of a spatula to heat the
stone that you use a heat lamp to warm the stone, pick it up with
tweezers, and put it onto the wax. Once the stone starts to settle
into the wax the heat lamp can be moved over the object until the
stone is at the right level. Remove the heat lamp and let the piece
cool.

Gerry Galarneau


#11

Ralph, It is very hard to imagine that your stone darkened from just
heating it with wax. The stones are embedded in hot sealing wax when
they are cut, and often heat treated to lighten them or change color.
If it has been cleaned of all surface contamination, and still shows
discoloration, I would begin to wonder if my Sapphire was really
corundum. There are plenty of look alike gem materials out there that
are temperature sensitive. If the stone is of any real value, perhaps
a check with your local GG would be in order.