Joyce - the beads aren't as uniform a color as I'd expect dyed beads to be, nor is the veining as dark as I'd expect dyed veining to be. But if they're really cheap...

Did you review the Wiki article? [Got any hydrochloric acid under the sink? Me neither.]

If it turns out to be turquoise, the next question is, Zachery or otherwise treated? The vendor should be able to tell you.

Chris

Probably magnesite. IMHO

Some of this stuff is soo good looking it is really hard to tell. The small amount of veining/crazing/matrix looks like real matrix. It's not over done to make it look like #8 mine or some other high grade turq with fine veining.

You don't need dilute hydrochloric acid, white vinegar is 5% acetic acid and will cause unstabilized magnesite to give off bubble of CO2. Even if stabilized with plastic that penetrates all through the stone a cracked open bead will slowly give off CO2 bubbles.

Thanks, Russ, for the acid tip! I was wondering if something other than hydrocholoric would work - maybe they use that because the reaction is more dramatic (the stuff foams)?

I imagine the aqua regia in a gold testing kit would cause magnesite/dolomite to froth, too.

Acid is, of course, a destructive test - it will dissolve turquoise - and I'd never recommend it on something one paid a lot for or didn't own yet... And watch out dripping it on a rounded surface, of course, 'cause the stuff will run off ;^)

I re-read the Gems & Gemology Spring 1999 article on the Zachery treatment for turquoise, and it contained the interesting information that an oxalyic acid soak will lighten the material and make it porous to the point of feeling sticky to the touch. But of course, destroying a valuable piece of turquoise just to prove a point is certainly not recommended.

Also useful was a description of the colored veining typical of the Zachery treatment versus the colored veining due to dyed polymer filling - in the former, the darker areas are alongside the cracks, in the latter, inside the cracks. In Joyce's sample, I saw what looked like blue-filled cracks, but without a close-up, of course, any photo ID is pretty much a best guess.

The article also described how the Zachery treatment works best on medium- to high-quality turquoise. Often Sleeping Beauty turquoise is a good candidate. The process takes 3 to 6 weeks.

In the 9 years since this article was written, has the Zachery patent been cracked/pirated to the point where it's in use anywhere else? When I was last in Tucson, two years ago, one of the better turquoise vendors had a booth devoted exclusively to Zachery treated turquoise, and the stuff was gorgeous. RH, of course, has sold it for decades, and they always disclose the treatment.

So, given the material and time requirements for the Zachery treatment, price ought to be an indicator - i.e., if the beads/carvings are cheap, suspect polymer or magnesite/dolomite. But has anyone ever encountered any pricey "bootleg" Zachery processed stuff?

Chris

Some years ago the Foutzes treated some stone from the Ma'ashan turquoise mine in Anhui province (Also known as Maanshan or Monshaun)that produced a lovely green stone. It was marketed under the name "Emerald Valley." Dee still has 10 strands of that strung into a necklace.

As far as I know the Zachary/Foutz process is still under their control. I haven't see any "bootleg" Zachary goods. On the other hand, I never see any new waxed Chinese turquoise. The wax process has been replaced by resin stabilizing.

Hi Russ,

I am not confident I know what the Zachary treatment is, nor how it may differ from any (other) plasticization process. I would presume the Zachary process is somehow superior to any other process—meaning it is difficult to distinguish, and not obvious like a bad treatment.

Current materials (meaning MORE than just turquoise) that are stabilized (or treated or hardened, or whatever) in China come out of the process being very hard (!). Whatever they are doing, the result is of a surprising hardness. I haven't actually tested it yet (though I suppose I ought to), but it was pointed out to me over a year ago that such beads, when they are clinked together make a high-pitched sound (indicating hardness). Last year, I bought a blue coral bead that did exactly the same thing—indicating it has been made MUCH harder than common blue coral ever would be.

I guess I am not surprised to read that waxing turquoise may have become passé. Once factories have a better process, that would become routine. And, clearly, over the past fifteen (or so) years China has made remarkable strides in plastics manufacture—now replacing formerly natural (like wood and bristle) products with mass-produced injection molded plastics and nylon. In a way, it's a shame. It is certainly polluting the environment.

We have to remember, though, the mine(s) in China AND the material they bring in to work on, includes turquoise of all sorts of qualities; from gem quality (meaning hard and colorful) to chalky pale stuff that has to be stabilized (and more) to have any value at all. While a LOT of turquoise is treated, not necessarily all of it is, and I would hope that some benign processes may still be exploited. Perhaps I am being naive....

For me, the question has become, not whether turquoise is treated or not, and how, but rather IS what we're being offered turquoise at all (?). So often these days, it is not turquoise.

I am always interested to read about your experiences and opinions.

Cheers, Jamey

Remember those inexpensive faceted Chinese freshwater pearls, produced by casting a pearl in some sort of hard resin and then faceting the resin?

It would be interesting to know what the most popular industrial resins are - presumably produced for industries outside the lapidary field, and thus comparatively widely available and cheap enough to make it economical to soak stone. There are so many substances and formulas out there now, I imagine there's a whole subsidiary industry that exists solely to crack and reverse-engineer competing products.

Melamine would be my guess.

Then there's the vapor-deposition and sol-gel processes...

Chris

Melamine is pretty hard - not as hard as many stones, certainly, but hard enough for tableware, furniture, industrial abrasives. Accepts colorful dyes. The resin has been used in the past to soak paper and wood in order to toughen up these substances. And it's easily produced from coal, which is possibly why China makes a lot of it. It's cheap and available enough to be widely used there to adulterate animal feed, so I thought perhaps it might also be chosen for soaking porous rock over the more expensive polyurethane resins or epoxies. Could be dead wrong, of course, and I don't have a Raman spectrophotometer expert handy to do any materials analyses with. Dang!

Here's a link about melamine-related stone sealants:
http://www.wipo.int/pctdb/en/wo.jsp?IA=NL1999000615&DISPLAY=DESC

I do have some odd big imitation amber beads which I suspect might be melamine and not phenolic. Will post pics later in a separate thread.

Chris

Whilst having a cup of tea I amused myself by Googling around for info on stone sealants. Silicone. But it doesn't last. So if that's what's being used in the Chinese stone factories, maybe in a few years these beads won't looks so great. But who cares - by then the fashion jewelry trade will have move on to something else?

And silicone products don't seem especially cheap, but maybe if purchased by the tankerful they're economical.

Chris

Good call, Chris, about the Chinese faceted pearls. I always wondered about them. I just did a little digging. Apparently at least one Japanese cutter does very precise faceting on thick nacre pearls. No coating involved. They have from 108 to 172 facets! I've seen these and they are very nice and very expensive.

http://www.facetedpearl.com/index/home.htm
http://www.gia.edu/gemsandgemology/18578/1801/523/back_issue_article_detail.cfm

The Chinese ones may very well be coated with very hard transparent plastic or glass. They are not precise, have irregular facets, almost free form looking and are relatively inexpensive. Here's some links about that.

http://www.yourgemologist.com/ISGForumsBoard/showthread.php?t=1299
http://www.ganoksin.com/orchid/archive/200105/msg00241.htm

We probably should have started a new thread about this topic.

Hi Chris and Russ,

I have been wondering about these pearls since I first saw them about five or six years ago. Curiously, the first ones I saw actually did appear faceted. No different from how a stone would be treated, except in a much small space of material.

I didn't get around to buying any faceted pearls until a couple of months ago. (After all, what do I need pearls for?) But at The Bead Museum I found some bronze-colored pearls that I could imagine actually using in a necklace as filler beads to the back of the design. BUT, at the time I bought them, I didn't think of them as being "faceted." To my (unaided) eye, they looked botryoidal. That is, having a lumpy surface, as happens with certain minerals (such as malachite). It wasn't until I got them home and had a chance to look at them under a magnifying glass that I realized they actually were faceted. But, what was happening was that the pearls have been lacquered (or plasticized, or whatever), and the faceting is actually applied to the coating (not the pearl). Each facet acts like a window, and causes a distortion, as happens with cutting through clear materials, that makes the interior surface magnify. (We see this all the time with paperweights, and some beads lately.) So, it is an illusion that the pearls look botryoidal. In fact, they are just coated and faceted.

I believe it would be impossible to coat pearls with glass. The temperature demands would cause the pearls to become destroyed. Whatever is done, it is a cold process, or one that does not require the high temperatures of glassworking and glazing.

Jamey

Jamey

My thoughts also that glass is too hot to case a cultured pearl. I mentioned that because the gemologist link thought they were looking at a glass coated pearl.

We've been chipping and cracking some "cheap" Chinese faceted pearls and don't see plastic. It really looks like the nacre is faceted. I'm going to saw a very round pearl in half to see what that looks like. from the edge.

"botryoidal" in appearance is a good way to describe the irregularly faceted ones from China. The Japanese ones were so precise and the facets so small that they had a much different look.

We really need a full blown gemological lab and a degree in forensic geology to do the full CSI workup on these beads. I just cracked open some "new purple turquoise" that is NOT made with COlbaugh's compressed dyed nugget purple turquoise made popular by Dakota Stones. This is a white material dyed blue then coated with a red dye that "takes" to varying degree on the surface. Vinegar did not cause the inner material to effervesce so it may not be magnesite. It has no plastic in the crevices so it is not stabilized. We called it "Imitation purple turquoise" for lack of knowing what white material was used.

...about turquoise:

http://www.delminsociety.net/motm/motm_sep2005.htm

In case someone needs a coffee break sometime.
Chris

This material proliferates on eBay, repped as genuine turquoise......98 cents opening bid for such a 16" strand pictured, repped as genuine material...