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Heat treated chalcedony gone awry?

Jewelry Discussion
#1

I purchased heat treated chalcedony beads a couple of years ago and
used them in an 18K gold wire necklace. I recently took the
necklace on a trip abroad, carried them in my hand luggage. When I
arrived at my destination, I found that the beads had lost their
beautiful rich blue color and faded into a pale moonstone like
color. Someone mentioned to me that this might have happened when
they went through the airport xray machine.

I called up the retailer of these beads, Fire Mountain Gems, and
they indicated they were not famiiliar with this type of problem
and had no suggested solutions.

  • Does anyone have a similar experience with heat treated gemstones?
    Was it really the result of the airport xray or something else?

  • Is there any way to reverse the effect without removing the beads
    from the gold necklace? And if so, is it something I could do on
    my own? Or are there any gemologists who specialize in this kind
    of repair?

I first joined the list in 1997 to pursue my jewelry making hobby.
It was the source of incredibly valuable I then moved
on to other things but now I’m back into it.

Thanks in advance for your help.

Best,
Rita

#2

Interesting - I too made a necklace with multicolor pink to blue
chalcdony briolettes only to notice last week that the colors had
indeed changed. They were not as bright, and one bead in particular
had turned a rather unpleasant green. I put it all down to heat
from the showcase lamps, but the necklace did take a trip across
country and through 2 airports… hmmmm. I wonder if heating
in the oven would help the color or make it worse?

Dina
@Dina_Weavers

#3

I’ve managed a retail jewelry store for the last 5 years and we see a
lot of beautiful beaded jewelry coming in and out. A lot of the
stones used in the jewelry we purchase are heat treated or "enhanced"
in some way. They are beautiful and vibrant when we first get them,
but they don’t last. We have had the most drastic problems with the
treated chalcedony. I’ve seen some turn very pale within a few weeks
of them being in the window. I love the colors and was thinking of
using them in my designs, but after seeing what happens to them have
decided against it.

I have even asked myself at the stone dealers that I have been doing
business with for years if these stones will fade, or what process
was done to them to make them that color. Shish! Every employee has
given me a different answer and not one has said that it will fade! I
don’t trust all this “heat-treating” but it seems like the majority
of stuff out there is heat-treated. How do you protect yourself and
your reputation against it?

-Amery

#4

Yellow-to-brown colored chalcedony is often heated to yield a more
orangy, or reddish-orange color. The chalcedony you’re seeing as
blue, green, pink, red, etc., has most likely been dyed, not heated.
However, new treatments for gemstones are invented daily, so
anything’s possible.

I suppose it is possible for an airport fluoroscope to weaken the
intensity of the dye, but I don’t know if that has ever been tested.
Heat is usually the culprit when treated chalcedony undergoes a
color change. This info comes from the GIA Gem Reference Guide.

James S. Duncan, G.G.
James in SoFl

#5 
    We have had the most drastic problems with the treated
chalcedony. I've seen some turn very pale within a few weeks of
them being in the window.

As I stated in the previous post, the heat from being in the window
is what’s causing your problem.

    I have even asked myself at the stone dealers that I have been
doing business with for years if these stones will fade, or what
process was done to them to make them that color. Shish! Every
employee has given me a different answer and not one has said that
it will fade! I don't trust all this "heat-treating" but it seems
like the majority of stuff out there is heat-treated. How do you
protect yourself and your reputation against it?

First, contact GIA and order a copy of their Gem Reference Guide. It
lists all popular their properties, the most common
treatments, the stability of those treatments and what affects them.

Second, enroll in a gemology course. Yeah, I know, every time I say
this, the most common response is “I can’t afford it” or “No way do
I have the time for that, it’ll have to stay a hobby for now” but
these are the same people who call themselves jewelers. Even the
ones who don’t call themselves jewelers, but simply want to buy gems
for their jewelry creations want some kind of magical way to avoid
knowing the subject. It seems everyone wants some kind of global
"Gemstone Police" to have all the knowledge and experience for them
so they can be protected against having to actually know their own
business.

I’ve said it before, but it bears repeating: “I sure am glad I
picked the doctor who actually studied anatomy.” Be the jeweler who
studied gemology.

James S. Duncan, G.G.
James in SoFl

#6 
 Interesting - I too made a necklace with multicolor pink to blue
chalcdony briolettes only to notice last week that the colors had
indeed changed

Any agate or chalcedony that is bright pink, purple, blue, green, or
teal in color has been dyed. The organic dyes are light–sensitive
and will fade with time, especially under sunlight or fluorescent
light due to the UV content. The most stable color seems to be green.
Once the color has faded, nothing can be done except to try more dye.
Beads and cabs may be treated by a different process than slabs,
nodules, and bookends. There are methods of coloring agate and
chalcedony that use inorganic chemicals and these colors (such as
black onyx) shouldl be stable. Heat-treated agate should also be
stable.

Ray