Tahitian Pearls Not Gritty?

[Daddys Little Pearl]

I am holding some baroque Tahitian cultured pearls, large sizes, purchased from a seller of good reputation who is known to this forum (not PP just to make that clear). They are beautiful, lustrous, cold, and heavy, all the things I would expect, with overtones, etc. Nothing at all to raise any flags at all. Only one problem. When I rub two them together, they do not pass the "rub together to feel grit" test. I am pretty new to tahitians, these were bought for my by a friend, but I selected them. Is there something unique about Tahitian pearls that makes them smoother? These are not strung in a necklace, loose pearls selected individually. Is there something I should look for to identify if these are not the "real thing".

 

[Lagoon Island Pearls]

Aragonite is white to light brown in color. Conchiolin is dark brown to blue black.

The ratio of mineral to protein along similar pearl grades of pearls or shells may vary a percent or two, but that margin appears wider between different colored pearls.

I have white ones and I have blacks ones. The whites are definitely more gritty than the dark.

The grit thing, is merely a rule of thumb guideline, usually applied to akoya or freshwater pearls... which tend to be whiter normally.

Although some are white, both South Sea and Tahitian pearls of larger Pinctada sp. have rich (yet not too rich like pens) near perfect ratios in their final grades.

 

[Daddys Little Pearl]

Thank You Lagoon Island, you lost me a little with the ratio thing, I am really new to evaluating pearls and studying on my own. Guess I have not made it to that chapter yet! I do get most of what you are saying, and since posting this question have been searching Strack's book, and reading up on "polymer coating" which is what I think these may have, although they were offered as having "no treatment".. Not sure if the polymer coating is a horrible thing or a slightly bad thing, Strack describes it and how to look for it, but does not elaborate on the significance of that treatment to any great extent.. Since these are loose on a holding string, I have been trying also to look down the drill hole with my 10 loupe ( don't own a microscope yet), to see if they are even natural color. As these were selected at random, and none are alike either in color or shape, some of the darker ones are definitely also darker inside, or at least darker than white. All of them have very much a "mirror" finish. Some do have mild surface blemishing, which according to her book, would have made these a good candidate for color or coating treatments. Will post photo shortly,

 

[pattye]

Well, I have some thoughts about this, but would need confirmation by someone with more experience than I have. When I do this test with my Tahitians and SS, it is a very subtle grittyness. I have much more experience with Tahitians, and limited first hand experience with golden SS and white SS. I think it is because the nacre is "tighter" and the platelets are not as open as they are on freshwaters. If I am gently rubbing north/south, but not feeling any resistance, sometimes it will be slightly more noticeable if I change to east/west.

If you trust the person you are buying from and there is nothing about the pearls' appearance, even under close examination/magnification to indicate they are not cultured pearls, I wouldn't be alarmed.

With experience you will learn to trust your eyes more and be familiar with the coloration of Tahitians and South Sea pearls. I will be interested in others thoughts on this subject.

 

[Daddys Little Pearl]

Here are photos, taken on a silvery gray background, all without flash under my Ott natural spectrum light, the last two photos with flash. I thought none of them passed the tooth test, but just found one that does for sure. This is my first time in my life to even touch a Tahitian pearl, so all this is very new to me, i am used to the touch of the nacre rich freshwater from Tennesee and China and the old Japanese Akoyas, all of which had real grit!.

 

[pattye]

Very definitely Tahitian pearls, characteristic irregularities and colors, dark charcoal background with varied overtones, others almost white with cool rings, what a fun assortment!

 

[Daddys Little Pearl]

Thanks Pattye so now I feel better about this purchase, but a little troubled as I have been depending on the "rub two together" test for my first test in pearl evaluation (actually second test, I do the cold touch test first, and these were ice cold). This means I may have passed up some "real pearls" in the past when the rub test produced no friction. Would love to know from the other pearl forum experts their experience in which varieties of pearls do not produce such friction, and also if anyone thinks the Tahitian pearls are being polymer treated, as Strack's book I think indicated this was being done to some extent, and if this is a bad thing if indeed these were so treated.

 

[Lagoon Island Pearls]

Do you know someone with a microscope? I have a 50 dollar USB microscope, well worth it.

 

[jshepherd]

Polymer is something that does happen (and is not necessarily disclosed) in Asia. If the pearls came directly for Tahiti you have nothing to worry about.

 

[Daddys Little Pearl]

Thanks Jeremy, they did not come directly from Tahiti, they are from an online seller (not from China) that has a good reputation ( I just hate to mention names as I don't think it is fair to the seller). So I do not know where they got them, but they do buy atthe big shows in Tucson and have had some pearls from Robert Wan in the past. Is there any way for me to tell if they are polymer coated, and is it even an issue; they are beautiful pearls regardless.

 

[jshepherd]

If they are coated, you should be able to prick them with a pin. The coating is thin, but somewhat similar to nail polish. I've only seen it on low-quality Tahitians and freshwater pearls.

 

[Daddys Little Pearl]

Thanks Jeremy, I just tried to prick one of them, slippery little suckers, almost stabbed myself, they are just too shiny slick to do a simple prick, so I got brave and tried to gash a tiny place with the pin several times (not recommended of course) and it produced very faint lines but did not penetrate the surface and the lines actually rubbed off some with my finger afterwards. So I guess no coating. So much for my confidence on the "rub them together" test. At least on Tahitians. Ok all you experts, are there other pearl varieties with this characteristic? So much to learn, so little time.

 

[Ash]

I still think they may be coated, yep will be slick. Best to try to peel the coating at a hole opening, Would certainly not think or say that Tahitians are not gritty when rubbed against the tooth or another pearl. I have one in a ring that does have a coating,which after years of wear & abuse is peeling off the pearl & where it is peeling off is where it is gritty when rubbed. The Pearl is 20+ Years old & was procured by a family member who worked in the jewelery industry at that time. Now retired.

 

[Daddys Little Pearl]

Update, today I was with a certified GIA pearls specialist who is huge in the pearl industry (sorry, don't like to call names without permission), and had them take a look at these Tahitian pearls. Opinion is that they are not coated, definitely Tahitians, some very good quality, some lesser quality. We did find some that had the grit sensation more than others; it seems that the shape has a lot to do with that factor at least in my group. And being genuine Tahitians they should have a good nacre thickness as well. Thanks to everyone for their opinions on this!