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Tanzanite fading in Sunlight?


#1

A very nice customer of ours lives part time in Florida and part time
in Virginia, where our store is located. She does a lot of jewelry
shopping in both locales. Today she stopped in and mentioned that her
jeweler in Florida told her that Tanzanite will fade in sunlight, and
that it is a particularly bad problem in Florida. I told her that
this was one Id not heard before, and so I present this to my fellow
Orchidians. Does Tanzanite really fade in sunlight?

Thanks, all!
Peggy Wilson
Harbor Jewelers
Chesapeake, VA


#2
Orchidians. Does Tanzanite really fade in sunlight? 

Most emphatically not.

Wayne Emery
www.thelittlecameras.com


#3
Does Tanzanite really fade in sunlight? Peggy Wilson 

Yes Peggy. Tanzanite is one of the materials most sensitive to direct
sun and certain high-intensity lamp lights. Customers can safely wear
it for daily use, but don’t leave it sitting on a windowsill.

Ray Gabriel
www.raygabriel.com


#4

Peggy, She’s probably confusing it with Kunzite.

Chris


#5

Peggy

I believe it’s kunzite that fades. Check the archives for previous
discussions.

best regards,
Kelley Dragon


#6
Yes Peggy. Tanzanite is one of the materials most sensitive to
direct sun and certain high-intensity lamp lights. 

I am curious, why do you say that? I have very extensive gemological
library and I could not find even a hint of such possibility. The
only
possible source for the rumor I can think of, is that pink variety of
zoisite ( tanzanite real name ) rosaline can be confused with
kunzite, which is affected by sunlight.

Leonid Surpin
www.studioarete.com


#7

Peggy, I’m a Colored Stones Graduate (GIA), tanzanite is stable to
light. Kunzite will fade.

Thanks -Chris


#8
I am curious, why do you say that? I have very extensive
gemological library and I could not find even a hint of such
possibility. 

Suspecting I might be wrong, Leonid, I did more extensive research on
this issue. Most of the gemology texts either don’t mention sun
fading at all or mention it only in regards to kunzite & topaz.

All blue tanzanite is heated and the basic material zoisite heated to
make several colors including tanzanite blue. Good quality material
is becoming increasingly harder to find - although this can always
change.

I did do a Google search on “tanzanite fading” and got a number of
articles on care of the finished stones set in jewelry. The two
warnings I found were not to leave it in strong sunlight and not to
clean it with an ultrasonic cleaner.

Since I can’t believe retail jewelers would mention the fading if it
were not real, I’m not sure who is right. As someone who is both a
jeweler and a gem dealer, I would suggest following “folk wisdom” and
be safe - don’t leave tanzanite (or any gem) in the strong sunlight
over a period of time.

Ray
www.raygabriel.com


#9

Does Tanzanite really fade in sunlight?

Yes. I had read that about Tanzanite as well as Amethyst (some other
treated stones too) but in 22 years never saw an example. Recently a
customer came in for prong work to be done on a ring bought at my
store years ago. This store had the very highest reputation then. I
knew it could not be low quality and could not be anything other
than what it was sold to be. After we discussed the work to be done,
she told me that these prongs had been rebuilt before (by this store)
and the work was good. Then she began asking if the color of this
Amethyst could have been the result of that work. No, I explained,
the stone must be removed to do this job. As she persisted, I took
another look. She said the stone had once been a deep purple. Now the
stone had a somewhat indefinable almost cloudy appearance and the
color was (at first glance) purple. On closer look, that ‘purple’ was
as obscured as it is in a synthetic ‘February’ birthstone. Not- the
deep purple you’d expect in a high quality Amethyst. I asked: “Do you
garden?” She said “Yes! I spend almost all my time outside and I live
in Fla.- I Never take off my jewelry”. I could only conclude that
’Aha!’ Now I see just what it would look like if it were affected by
sun!

J.


#10

this has confused me, I never realized any gem could actually lose
color or fade the way clothes can, I was apparently, erroneously,
that the color was, pardon the pun, written in stone. Is this also
true for other gemstones as well? and if so why?


#11

Thanks, everybody. I thought I knew that Kunzite was the one that
fades, but wanted to double check with folks who know more than I
do. But clearly, based upon the responses, there are still some out
there perpetuating a myth. I would love to know where that idea
comes from!


#12

Debra, are you familiar with the color change phenomenon?

And, I cant remember which or how accurate this is but I’ve heard
malachite or hematite will turn skin red.


#13

Ray, Peggy,

Tanzanite cant take heat or sudden temperature change so no
ultrasonic, strong sunlight, etc. Oh, and no hydrochloric or
hydrofluoric acid… whatever that is. So dont leave it on an expired
car battery after…


#14
And, I cant remember which or how accurate this is but I've heard
malachite or hematite will turn skin red. 

Malachite is copper carbonate, which, not surprisingly, is green,
even when ground to a powder. If it turns skin red, then it might be
the owner of that skin is allergic or otherwise sensative to copper.
But that wouldn’t be unique to the malachite. Any copper source would
do it.

Hematite, on the other hand, is iron oxide. Grind it up very fine,
and you have red rouge. It might be possible, especially with some
cosmetics that might act as polishing/abrasives against the solft
hematite stone, to get some to rub off which would indeed turn skin,
or clothing, red.

Peter Rowe
Seattle


#15
Tanzanite cant take heat or sudden temperature change so no
ultrasonic, strong sunlight, etc. Oh, and no hydrochloric or
hydrofluoric acid.. whatever that is. So dont leave it on an
expired car battery after.. 

It’s not even that tanzanite can’t take heat. After all, it owes
it’s purple color to having been heat treated. As you say, what it
cannot tolerate is sudden temperature change. Ultrasonics are a no-no
because tanzanite sometimes is under considerable internal strain due
perhaps to the heat treatment it got. Some of them will shatter in an
ultrasonic. Now, I’ve cleaned a lot of smaller less expensive ones
with both ultrasonics and steam cleaners, but I’ve also broken one or
two over the years (also cheap ones) with the ultrasonic, so don’t
use that on anything you’d mind replacing or a larger higher quality
stone.

Car batteries use sulphuric acid, similar to what used to be used in
pickle pots (and sometimes still is) before most people switched to
sulphuric acid salts. The salts (sodium bisulphate, such as Sparex or
similar) are just as corrosive to those things they affect, including
some stones, but are safer in terms of fumes and ability to burn
skin. I’ve not seen tanzanites be damaged by normal immersion in
pickle, which can be considered dilute sulphuric acid, but I wouldn’t
leave it in there long periods. Hydrochloric, you’re not likely to
be using. And Hydrofluoric you most certainly should NOT be using
unless you’re well equipped to handle this very dangerous acid.

By the way. For those who wonder whether tanzanite is indeed
sensative to sunlight, despite what most here on the list have said,
consider what the damage ultraviolet light (sunlight’s most damaging
part) does. It conveys enough energy to a stone’s atomic structure as
to allow some change, such as knocking an electron out of one orbit
to another different energy one, or otherwise doing something that
affects light absorbtion. It can be compared to annealing in a sense.

Those stones that are sensative to ultraviolet light are generally
also sensative to heat, which is also energy. The amounts of heat
(infrared) needed to make a change might differ from the amounts of
ultraviolet, but you can be fairly certain that a stone like
tanzanite that owes it’s current color to a prior significant heat
treatment, won’t then care about a bit of ultraviolet, since it’s
unlikely that the energy input to the stone from sunlight could
exceed what went into it from heat treating. If it was heated and
then irradiated, well, then this no longer applies.

In general, stones sensative to fading in sunlight are stones that
have NOT been heat treated as the most recent treatment. They often
are either stones that have never been treated at all, and normally
are not exposed to sunlight or high energy during formation, or are
stones which owe some portion of their current color to either
natural or artificial radiation. Treating stones with irradiation
generally affects the color often by doing the exact opposite of
what lower energy ultraviolet can do, that is it induces some damage
to the atomic structure, or knocks some electron to a higher energy
orbit where it remains trapped until something coaxes it back down.

Some early forms of irradiated blue topaz would fade in sunlight
over time because of this, untill the treaters learned how to
irradiate the stones in ways which didn’t leave them susceptible to
this. And I remember when a couple years out of college, too many
decades ago, buying a lovely and inexpensive parcel of luscious rich
brownish orange topaz from mexico. Not even in direct sunlight, but
just in a gem tray in normal room light, within a month or two,
they’d faded to a pale light boring tan. Clearly irradiated stones,
though I’d been told they were natural. It was an experience that was
influential in prodding me to start gemological training with GIA…

Hope that helps.

Peter Rowe (G.G., '79)
Seattle


#16
But clearly, based upon the responses, there are still some out
there perpetuating a myth. I would love to know where that idea
comes from! 

Tanzanite can be fragile. Easy to damage in setting. Don’t go near
it with a torch. Can be damaged in the ultrasonic (few other commonly
seen stones need that particular caution), as well as an overly
enthousiastic blast from a hot steam cleaner. In short, it’s a stone
you have to be quite careful with every step of the way in jewelry
making. Plus it gets it’s color only after a careful heat treatment,
and then has the best color only if the cutter oriented the material
correctly. All in all, it’s pretty unique material, and no doubt,
someone somewhere just got overly enthousiastic with caution, and
it’s been passed along. The “better safe than sorry” theory…

Peter


#17
This store had the very highest reputation then. I knew it could
not be low quality and could not be anything other than what it was
sold to be 

If that amethyst was needing its third set of prongs the crown would
be rather abradified. Particularly if she gardens with it on.
Seriously abrasion can affect the perception of color intensity.

I think its risky to draw gemological conclusions based on the
owners’ recollection and impression or the seller’s reputation some
years ago. Anything could happen in the interval.

I’ve had people swear up and down at me that something WAS INDEED as
they claim, when viewing the stone even at arm’s it was clearly not.
“But Granny never bought junk”. “See these curved lines Madam”

One should not normally display a tanzanite(and a few others) in a
sunny window, not because it will fade, but because heat buildup in
an small enclosed, unventilated showcase with hi power lighting
blaring down on it is going to be a problem. In the vast majority of
cases nothing happens. But there’s always that oddball case where it
does. So the oral tradition says ‘no tanz in window’… over time
and many ears/mouths that gets interpreted as sun will fade it.
Because people make assumptions.


#18
spend almost all my time outside and I live in Fla.- I Never take
off my jewelry". I could only conclude that 'Aha!' Now I see just
what it would look like if it were affected by sun! 

You are right about amethyst, but tanzanite is a different matter.

Leonid Surpin
www.studioarete.com


#19
Is this also true for other gemstones as well? and if so why? 

Some gemstones are affected by sunlight. As to why, the subject is
quite complex and different gemstones have different reasons.

In a very relax manner of speaking, color in a gemstone is the result
of presence of an impurity, or a structural defect that alters color
absorption of the gemstone. Sunlight is a form of radiation which can
change the impurity, or the character of structural defect, and
thereby changing the color of a gemstone. Most of the time it results
in fading of the original color.

Leonid Surpin
www.studioarete.com


#20
Since I can't believe retail jewelers would mention the fading if
it were not real, 

You have a lot more faith in retail jewelers’ omniscience and
infallibility than I do.

Al Balmer
Sun City, AZ