Monday, May 23, 2011

Pearls - Looking at the inside !

The first thing to point out is that there are several types of oysters and mollusks that are used to produce pearls, both salt-water and freshwater. I am not going to go into the different kinds of pearls in this discussion, just what the inside of all of them basically look like. Borrowing some photographs from the International School of Gemology (ISG) where gemology is taught based on actual specimens of gemstones: natural, synthetic and organic, rather than from pictures in books, we will take a look at the inside of a pearl For this discussion, the internal differences between a salt water Akoya cultured pearls and a Chinese freshwater cultured pearl will be looked at. At the end, a new surprising find will really make one wonder.

Above is seen a 5mm pearl purchased as an Akoya cultured pearl. Notice that it is uniformly round from the seed all the way out to the outer nacre layer, which is the thin line you see at the very edge of the pearl. What was quite remarkable about this pearl is that the center of the pearl is a hollow plastic looking bead, not the Mississippi mussel shell bead that was expected. You can see the circular structure of the Akoya cultured pearl with the bead and resulting layers being rather uniform from center to outer nacre layer.

Now above you see a freshwater cultured pearl from China . These are called non-nucleated pearls since they are started with a ball of tissue rather than a pre-formed bead. The picture is quite graphic to show that the center of this pearl is a somewhat organic looking mass of old tissue rather than a well formed starter bead as seen in the Akoya pearl. These pearls have been back lit to allow one to see the difference in formations, which is rather pronounced and graphically demonstrates the basic difference between the salt water Akoya and the freshwater pearl.


A question was asked that perhaps since the freshwater pearl was started by what is basically a ball of tissue, that should there not be some kind of hollow place in the center of a freshwater pearl as the tissue degenerates during the growth process? And sure enough, when the viewing angle is changed on the freshwater pearls, one can see hollow places in the pearl as seen in the pictures below of a half drilled 5mm freshwater pearl.

Thus these pictures show what would be seen if you dissect one of those expensive little jewels you have on that string of pearls you got as a gift.


Now for the surprise. How about opening up one of those very expensive Tahitian South Sea Pearls which are known for their excellent quality and thick nacre layer. But what’s really inside one of those Tahitian pearls? Well, one was cut open and to the surprise of everyone, what was found is almost beyond comprehension !

The center is a plastic bead. Apparently someone has found out how to use plastic instead of natural material to get the Pearl to form.

And taking it one step further, perhaps a reused piece of plastic for the starter bead. Why the multiple holes in the starter bead? Was the pearl farmer recycling plastic? Why place a used, multi-drilled plastic starter bead inside an oyster to make what could turn out to be a very expensive South Sea Tahitian Pearl in the first place?


But then again, it is this type of perplexing problems that is what makes gemology so much fun and of interesting experiences. A lifetime of learning and sharing the wonders of the earth.


Again thanks to the ISG for the use of pictures and information.