Fake turquoise - What is it?

I bought some turquoise at the weekend. Nice looking piece, but I paid
very little and bought it from a retail "shopping mall" fossil shop, so
work it out for yourself.... I'm in the UK BTW, so it's not a local
stone, nor common, and I certainly don't know anything about it myself.

My plan was to saw it down and then mount the interesting
pyrite-speckled half in a simple silver bezel as a pendant. That's one
Christmas present sorted and I could use the silversmithing practice
(this would only be something like my 3rd set stone, so I need the
practice).

When I came to saw it though, I was surprised to find that the insides
were a hard pure white, like porcelain. I was expecting some degree of
fakery, but this much was a surprise. I'd expected to be buying
low-grade turquoise that might have been heated / dyed / soaked in
badger's urine to "improve" it, as is usual for so many stones today.
This looks like it's a total fabrication though - as if it's a blob of
procelain, then painted on the outside.

Any guesses as to what I've got here?

Should I carry on mounting it? 8-) So long as it's in a solid-backed
mount, then it doesn't look bad...

On Tue, 28 Nov 2006 08:20:03 -0800, in rec.crafts.jewelry "Andy Dingley
" wrote:

When I came to saw it though, I was surprised to find that the insides
were a hard pure white, like porcelain. I was expecting some degree of
fakery, but this much was a surprise. I'd expected to be buying
low-grade turquoise that might have been heated / dyed / soaked in
badger's urine to "improve" it, as is usual for so many stones today.
This looks like it's a total fabrication though - as if it's a blob of
procelain, then painted on the outside.

Any guesses as to what I've got here?

A first guess would be dyed Howlite. Howlite is a white mineral that forms in
veined/matrix bearing structures somewhat like turqoise, and is porous enough to
be dyed (It's dyed many different colors, but the turqoise one is especially
convincing)

I could also easy be a glass or as you describe, ceramic product. Howlite is
softer than either of those, closer to turqoise itself, which might help you
decide.


Should I carry on mounting it? 8-) So long as it's in a solid-backed
mount, then it doesn't look bad...


If you like it, and don't mind the identity, then sure. Good practice. Lots
of silver jewelry has been made with faked stones, and it can look just fine,
and is good practice, so long as nobody is fooling anyone with fraudulent claims
of gem identity or value. Whether you still wish to use the result as a
Christmas gift might be another issue to address seperately...

Peter

Peter W.. Rowe, wrote:

A first guess would be dyed Howlite.

How deeply does it dye? This really looks more "painted" than dyed. In
cross-section the coloured layer is very thin. It also shows some sign
of buffing off, where I've been clamping the stone. I knew the strong
blue of this stuff (hardly greenish at all) was too good to be true!

I could also easy be a glass or as you describe, ceramic product. Howlite is
softer than either of those, closer to turqoise itself, which might help you
decide.

I'd estimate about 6 Moh, so seems too hard for Howlite or Magnesite
(as was suggested by email). I suspect it's a deliberate fake with some
fired ceramic.

On Tue, 28 Nov 2006 19:44:58 -0800, in rec.crafts.jewelry "Andy Dingley
" wrote:


Peter W.. Rowe, wrote:

A first guess would be dyed Howlite.

How deeply does it dye? This really looks more "painted" than dyed. In
cross-section the coloured layer is very thin. It also shows some sign
of buffing off, where I've been clamping the stone. I knew the strong
blue of this stuff (hardly greenish at all) was too good to be true!

Howlite takes a dye better than that. It doesn't penetrate all the way through,
but you'd certainly see, on a cut face, some penetration. It's been a while
since I played with such a piece, so I can't give you a more precise answer for
sure, but I'd expect at least a millimeter or so of good penetration of the dye,
with lesser penetration going deeper. Might be wrong on that, but that's my
memory of it.

I could also easy be a glass or as you describe, ceramic product. Howlite is
softer than either of those, closer to turqoise itself, which might help you
decide.

I'd estimate about 6 Moh, so seems too hard for Howlite or Magnesite
(as was suggested by email). I suspect it's a deliberate fake with some
fired ceramic.


If it seems like just a hard surface glaze or paint, then it's not likely to be
Howlite, I'd guess. And Howlite is 3.5 on the mohs scale.

http://www.galleries.com/minerals/si...te/howlite.htm

Ceramic fakes are quite common too. Just not as convincing. They feel wrong to
me, or at least that's the best I can describe it. And with a loupe, they
quickly look all wrong too.

Peter