Recently in October of 2011 I sold a an 8mm round 2.59 carat vivid
yellow Hydrothermal sapphire to a customer as a center stone for a
engagement ring . The customer went on a trip to Florida by plane,
during her stay the stone faded to colorless. I have returned the
stone to the supplier who spoke to the lab in the Ukraine they said
that the stone gets its color from, something called " nickel 3 ",
and that exposure to the X ray scans in airports causes the " nickel
3"which causes yellow to become " nickel 4 " which causes white, and
thus the color fade. The suppliers says this can happen in natural
sapphire the same as the hydrothermal lab grown. Is this true ? and
if so has anyone else seen this happen? or is this not true ?
G.I.A.: Colorless to yellow to intense orange sapphire will react
quite differently to light or heat depending on the nature of the
material and the origin of the color. The authors determined that
there are actually seven types of “yellow” sapphire on the market
today, which differ in the cause of color and the stability of the
color to light: type 1. natural, light-stable color center. type 2.
natural or irradiation-produced, fading color center. type 3. iron
containing, not heated, light stable. type 4. iron containing,
heated, light stable. type 5. surface-diffused additive, light
stable. type 6. synthetic, light stable. and type 7. synthetic
irradiated, fading. The authors examined more than 150 samples of
yellow sapphire to confirm the seven types and document their
different reactions to light, heat, and/or irradiation. One
unexpected finding was that type 1 material can fade on heating even
below 200 C, but that the color is restored by exposure to light.
The difference between Nickel 3 and Nickel 4 is the electron
arrangement in the atoms for making compounds, and producing color.
What happens is that the xray machine introduces enough quantized
electromagnetic packets into the atom of Nickel 3 to cause the
electrons in the outer shell to take on the structure associated
with Nickel 4. Because of the electron arrangement, each of these
atoms will react differently to light and other processes.
I’ve never known of any natural sapphire to fade except in the case
of extreme over-heating by a negligent jeweller. I imagine every day
1000’s of sapphire rings are going through airports around the world.
If they faded from x-rays I think we’d all know about it by now.
My own rule is only buy natural stones, either untreated or only
with currently known treatments that are stable. If they wanted a
yellow stone you could have sold them a nice bright lemon Citrine
which you can buy for most gem dealers for not much more than the
courier charge. There are many gems available that are nice & cheap
enough without having to go for these hydrothermal, synthetic or
other man made gems. My opinion it’s best to avoid them altogether.
It has been reported that the color of pale yellow sapphire is being
intensified by exposure to radiation. Unfortunately the color is not
permanent, but fades after a while in sunlight.
The customer went on a trip to Florida by plane, during her stay the
stone faded to colorless. Sounds to me like the company is feeding
you a line. I don’t believe an airport x ray is strong enough to
have any effect whatever on any gemstone.
There are many half-truths in that story. I cannot pass judgement on
whether many half-truths taken as a whole make a truth or a lie?
Here are few facts:
Lab-grown sapphires can lose color, but only if original color is
a result of irradiation and not doping with nickel III.
Can natural sapphire lose color ? While everything is possible,
practically the answer is no. Natural sapphires that we find are
millions of years old and have been exposed to everything, so the
color that we get is quite stable.
Can airport scanner change the gemstone? Only extremely unstable
(cannot even be called a gemstone in this case) and even that is
highly questionable. If scanners are that powerful, think what they
would they do to laptops, digital cameras, and etc.
The main point here is if something is called gemstone, durability
is implied and a part of gemstone definition.
Sorry but I must take exception to Phil’s comment about synthetics.
True synthetics that are chemically doped for color stable. In fact
to be a synthetic they have to be chemically the same as the mineral
they are replicating. If you were to take a synthetic and a natural
sapphire and pulverize them and analyze the chemical structure of
each you would find they were the same within the allowable delta
deviation for such things as location. As in the deviation you would
see examining sapphires from say Montana, Cambodia, and Australia.I
do agree buy Natural when you can find and afford it. But if a near
perfect stone as an end product is your desire, and you don’t have
the money to pay $1000.00/ct. for your rough a synthetic at a couple
dollars or less per ct. is very appealing. And every bit as beautiful
and durable as the Natural. Just be honest about the disclosure as
you should be with ANY treatment.
Lab-grown sapphires can lose color, but only if original color is
Leonid - I am accepting this from you as Factual the forensics of the
situation seem to support a poor quality of irradiation in this
hydrothermal material now i have to think of a polite way to call my
supplier a liar and still be able to get my money back - goo