Of all the different types of gemstones that are mined and commercially sold, the pearl is the only one which is not a mineral. Pearl stone is organically formed by living organisms. A pearl gemstone is formed inside a mollusk shell. When an irritant like a sand particle gets inside the shell, the mollusk adds on layer after layer of nacre around it.
These layers are deposited concentrically one after the other. Chemically speaking, a pearl is composed of calcium carbonate. Pearls could be created naturally or they could be created by humans. There are many types of pearl gemstones including a Basra pearl stone, and some of them are listed below.
As mentioned above, these are pearls formed inside oyster shells naturally without any human intervention. But because they are so valuable, they have been harvested at a very fast rate, and therefore are very rare to find nowadays.
Because natural pearls were so rare and their stock got exhausted, we developed the technique for creating pearls synthetically. These pearls are called cultured pearls. The starting point of such a pearl is the bead of mother-of-pearl which is inserted into the mollusk shells.
This is a saltwater pearl stone mainly grown and harvested off the coast of China and Japan. These are comparatively smaller than other types. The size of these pearls ranges from 2 mm to 10 mm. You would find them in cream or white colors. The source of these pearls is the Pinctada fucata martensii oyster.
South Sea Pearl
This also is a saltwater pearl found in the seas of South Asia. You will find these pearls in Indonesia, the Philippines, and Australia. They are much larger than the other freshwater pearls and the Akoya pearls named above. This oyster is more rare and sensitive, therefore the cultivation and harvesting are more difficult and time taking, making these pearls more costly.
This is called a black colored pearl, though you will also find it in other colors like blue, green, grey and purple. The most valuable varieties of the Tahitian pearls are the darker and black shades. These pearls are harvested from the pinctada margaritifera oyster.
This is one of the larger varieties of oyster, therefore these Tahitian pearls are also comparatively larger. It takes almost two years for these oysters to mature and produce a fully developed pearl. Tahiti is the largest island of French Polynesia, and these pearls make up more than half of the annual exports of French Polynesia.
This kind of pearl is called blue but in different kinds of light, it can appear different. The genetic makeup of each individual mollusk provides these blue pearls their distinctive shade. When there is a marked variance in the temperatures of water in which these oysters are found, then it gives additional layers to the shades of the pearl gemstone.
In the Indonesian islands where these blue pearls are very common, there are old legends which say that the colors of these pearls were provided by the Gods by mixing the cool blues of the oceans and the dark greens of the forests.
These are the most commonly produced pearls. They come in a wide variety of colors and shapes. The most common shapes are baroque and round. Their surface texture is quite different from the other pearls mentioned above.
A single freshwater pearl mussel can produce as many as 50 pearls at a time, which is why freshwater pearls are so popular with harvesters and seller. You might find it a little difficult to distinguish between the Akoya pearls mentioned earlier and the freshwater pearls.
Instead of being grown inside the body of a mollusk-like most of the other pearls on this list, this pearl is grown against the inside of a mollusk shell. They are quite similar to South Sea pearls but can be obtained at a much lesser price.
They have a flat back, and so are quite popular in making fine earrings, rings, and pendants. A mabe pearl is produced by inserting a nucleus into the oyster shell after which the shell is returned back to the water. The oyster takes many months to mature.
The name for this pearl stone is taken from Japan. These pearls are usually oval, flat, or almost-round. You can find these pearls in a number of colors like grey, black, white and others. These pearls are quite glossy. The word Keshi literally means poppy seed.