FMF - Friends of Minerals Forum, discussion and message board

[Carrington]

Hello everyone,

I have a question regarding the stability of color in Topaz.
In the past there was a find at El Chalten which produced lovely cognac-brown colored etched topaz crystals.
Recently in Colorado the Tribute pocket in Pikes Peak produced etched topaz crystals with a similar color.

I know that the El Chalten topaz crystals are not very color stable and have seen the effects. I am not sure if the new Colorado examples are color stable. I think the color on these Colorado pieces is richer, almost a tangerine color.

I have an etched topaz crystal from Yuno in the Shigar valley which has a natural similar color to the examples from these 2 localities I mentioned above. My problem is I do not know if my topaz has stable color. Does anyone know If the Pakistan examples are stable? I presume my Pakistan topaz is also not stable, but would appreciate any further information. I like to display my specimen but am worried about color loss.

[Joseph DOliveira]

[alfredo]

Brown topaz from both the USA (Utah) and Japan fades in the light, eventually to almost colorless. I suspect that brown topaz from any locality will be the same, unfortunately.

[Josele]

My experience with Pakistani topaz is that color do not fade along time.
I don't know if darker specimens are irradiated but anyway brown and champagne color has remained stable along the years.
I must add that my specimens are in darkness most of time, except when they are out off his cabinet.

BTW, completely in accord with Joseph relative to green spodumenes from Afghanistan: they loose most of green color very fast (even kept in darkness) and some dealers recognize they are treated.

[Bob Carnein]

According to Rich Fretterd, who, with Jean Cowman, found the Tribute pocket, the topaz from that locality is stable in incandescent light but fades in direct sunlight.

[Jordi Fabre]

Please check: All Topazes are sensitive to the sunligth?

[Josele]

As seen, this is a recurrent topic without unequivocal answer. Some topaz specimens fade undoubtedly and others seem to be stable, at least under normal storage conditions.
Who knows what could happen if we let one of these stable topaz under sunlight for a long time, probably will fade too, as they do many other minerals.

[Peter]

Natural champagne topaz do fade in the sun.
Blue do not fade but may intensify.

I wish people stopped buying irradiated brownish Paki topaz.
There is so much colorless topaz of less value to irradiate so when one wants to be cheap and buy brownish-orange for a fraction of a natural one....
Well, just waste your money!

[Carrington]

Thanks for the clarification everyone.

I am confident the color in my topaz is natural, as it did come from a reliable dealer who would note any treatment done to the specimen and also does not like to sell specimens that have been treated.

I will just be careful with this specimen and the time I expose it to light.

[Peter Megaw]

Not all Mexican topaz is created equal...Villa Garcia material seems pretty color stable but that from Tepetate is not. Likewise that from the Black Range in New Mexico

In the earlier thread on this topic that Jordi has highlighted above Ed Huskinson expresses a sound philosophy...if you assume all colored minerals are light sensitive and keep them from excessive sunlight you will never suffer color loss.

[Scarodactyl]

There is a faceter who has posted pictures of a couple of topazes he's faceted from the Tribute Pocket material. He says that he left one of the stones in sunlight and it appeared to be stable. I don't know for how long though.

I have yet to find a Pakistani igneous topaz which did not fade to colorless when exposed to sufficient sunlight (a depressingly small amount, only a few hours of direct exposure). That said, I believe that the specimens I have tested have all been irradiated, as evinced by color zoning that I would describe, in technical terms, as "wiggidy" (internal phantoms, only one edge being colored, tiger stripe patterns, etc etc). As Peter said these irradiated stones are sort of a waste of money, but they seem to hold fine if not constantly exposed to light, and the highly unnatural color zoning and very distinct pleochroism make them amusing regardless.

Metamorphically-formed topaz from Katlang is a very different beast. Katlang is famous for its chromium-colored (and thus color-stable) pink-to-magenta topaz, but a parcel I purchased were an intense fanta orange color with hints of red (not perfectly conveyed in the attached photo, but it gives an idea). These stones occur in metacarbonates similar to fine Brazilian stones and have a similar crystal form, with classic "imperial"-looking terminations, though they tend to be etched. Long story short, the color of these stones was likely the result of this material's unique response to irradiation, and quickly faded in sunlight down to a pale pink-champagne color, with pink most visible on the AB axes and yellow down the C. This color is, according to an article in Gems and Gemmology, the result of a tiny pinch of chromium (much less than the precious pinks) and as such is unlikely to undergo any further fading. And this was indeed my experience--the orange color was gone in three days, but the pink was unaffected by a further two weeks of summer sun exposure.

When it comes to Mexican topaz, the famous gem material from the Guerrero mine (from the 50s and 70s, long closed now) is known for its color stability (though it is not a universal property of all stones from there). These stones show a tan AB color, and a peach-to-bloodred c-axis color, quite unlike other Mexican topaz I have seen. I have left a parcel of these in direct sunlight for two weeks and not observed any noticeable change.

I also have a small parcel of coffee-brown topaz that my father purchased as colorless stones when he was in college, and subsequently had irradiated at his college (good old days). They look a lot like San Luis material. Decades of indoor storage later they have all of their color, but give one a couple hours in direct sunlight and they're back to their natural colorless state.

@Joseph: When it comes to color instability, perhaps the spodumene family, irradiated and natural alike, can serve as a reminder that, for topaz, it could still be worse.

[disconeckted]

Paki and Russian pink topaz ownership was restricted to the Czar and his family and those to who he gave it as a gift. They must keep their specimens in the dark!

[Riccardo Modanesi]

Hi to everybody!
The issue about colours of topaz is not so difficult: if topaz is just irradiated, electrons get imprisoned in the ALREADY existing colour centers and colour the crystals in pale blue, or orange, or pink...
If the specimen is submitted to radioactive bumbing, NEW colour centers are created and a successive irradiation give it a much more intensive colour (i.e. an intensive brilliant blue, or orange, or pink...). But you have to pay attention in wearing it: those specimens are somewhat radioactive! If you keep just as a collection specimen it's ok, as well as we usually keep our uraninites etc. If our ladies wear it every day, it might be somewhat dangerous.
Greetings from Italy by Riccardo.

[Ed Huskinson]

Thanks Pete, for the reference re photosensitivity.. When will we be seeing something in print on Santa Eulalia? Just curious as to whether you have a sense of it yet.

''sta luego,

Ed