Pearls have
been treasured for their splendor and rarity for over than four thousand years.
All around the world pearls have been valued longer than any other gem. They
are the only gemstones grown from a living organism.
When a
foreign substance (most often a parasite - not a grain of sand) are introduced
within the oysters or mollusks Pearls are made. This foreign substance enters
the soft mantle tissue and in resonse to the irritation the mantle's epithelial
cells form a sac (known as a pearl sac) which secretes a crystalline substance
called nacre, the same substance which makes up the interior of a mollusk's
shell, which builds up in layers around the irritant, forming a pearl.
