One of the first known gems to be valued by people, pearls have mystified and fascinated the minds of humans for centuries. Gemologists classify these beauties, whether natural or cultured, as colored stones. However, unlike most colored stones that people are familiar with such as rubies, sapphires, aquamarine, tanzanite, etc. – which are minerals – pearls are organic gems. Organic gems come from things that were once living or were produced by a living organism and include not only pearls, but amber, coral, ivory, and jet.

All natural or cultured pearls are formed inside of mollusks.  Mollusks are soft-bodied marine animals that normally have one shell or two. Examples of one shelled mollusk are abalone and conch and two-shelled mollusks are scallops, oysters and clams.

Pearl producing mollusks live in saltwater and freshwater.  Two terms which the general population and those in the jewelry industry regularly use to distinguish freshwater mollusks from saltwater mollusks are mussel and oyster.   Mussels refer to a pearl-producing mollusks living in freshwater while oyster refers to a pearl-producing mollusk living in saltwater.

A pearl is the beautiful, organic gem that forms inside the body of a mollusk (saltwater or freshwater) when a parasite or another foreign matter enters the body of the mollusk.  There is a natural substance which mollusks produce that cover the inside of their shell.  This is called nacre (NAK-kur). When the above mentioned parasite or foreign body enters the mollusk it will deposit this same substance over the object to soothe the irritation, thus forming what we call a pearl. 

South Sea Cultured Pearls:
Pinctada maxima (silver-lipped or gold-lipped oysters)
South Sea Cultured Pearls are saltwater pearls – bead nucleated – and are found throughout much of the southern Pacific, with Australia, Indonesia, and the Philippines as the principal areas for commercial farming. The most rare and also largest mollusk, the Pinctada maxima can produce exquisite pearls in colors such as white and golden from the silver-lipped oyster (which can have overtones of rose, green or blue), to yellow and yellowish orange/golden from the gold-lipped oyster. Their nacre is thick (ranging from  2mm to 6mm), produces a soft glow vs. a metallic sheen, and is formed more rapidly than oysters in cooler climates. South Seas cultured pearls can be round, near-round, oval, button, drop, baroque, semi-baroque and circled. They range in size from approximately 10mm to 15mm and are most often the largest cultured pearls on the market.

Tahitian Cultured Pearls:
Pinctada margaritifera (black lipped oyster)

Tahitian Cultured Pearls are saltwater pearls – bead nucleated – and are found mostly around the islands of French Polynesia.  Because of their dark colors, they were dubbed “black pearls” and first appeared in the international market in the mid 1970’s.  Not technically cultivated in Tahiti (culturing takes place on various other islands in French Polynesia), only a portion of the pearls cultured are actually dark enough to call ‘black’ as most of the colors produced range from blues, greens, gray and browns. Currently, cultured pearls are Tahiti’s biggest export and remain vitally important to their economy.  Tahitian cultured pearls can be round, near-round, oval, button, drop, baroque, semi-baroque and circled (circles occur on approx. 25-30% of Tahitian cultured pearls) and their size can range from 8mm to 14mm, with some rare ones getting as big as 16mm to 18mm.

Keshi Pearls:
(Keshi – Japanese for ‘poppyseed’)
An accidental byproduct of the saltwater and freshwater culturing process, happening either when the mollusk expels the implanted nucleus but the mantle tissue implant remains, or when dislodged cells from the mantle tissue produce the growth of keshi pearls. They come in a variety of sizes and colors and are mostly irregular in shape. Some people consider these good pearls to collect, since they are close to natural pearls (almost completely nacre) and because their shapes can be so odd.

Blister Pearls:
Blister pearls are cultured in saltwater and freshwater and are grown attached to one side of the mollusk’s shell and one side is without nacre and flat.

Mabe Pearls:
Mabe pearls are ‘assembled’ cultured blister pearls. Cut from the shell, the nucleus is removed and the ‘hole’ that is left is filled with epoxy resin (or a bead in some cases) and it is then glued to a mother-of-pearl (nacre) backing.

Conch and Melo Melo "Pearls":
Conch "Pearls" and Melo Melo "Pearls" are produced by two types of mollusks, the Conch and the Melo Melo snail. 
They produce "Pearls" that are non-nacreous and gem experts don't consider them true pearls because of this - thus refer to them as "Pearls", with quotation marks. 
Very rare and desirable gems, the conch and Melo Melo "pearls" and are not cultured, but occur naturally.
Usually fetching very high prices, the beautiful Melo Melo Melo "pearls" are among the rarest gems on earth and both the Melo Melo and Conch "Pearls" are highly sought after by educated collectors.

Fun Tales, Folklore, Facts and more,...

Elizabeth Taylor owns a famous, natural pearl called the La Peregrina. La Peregrina is a drop-shaped pearl that was owned by royalty since its discovery in the sixteenth century until 1969 when Rich Burton purchased it for Elizabeth Taylor. Mr. Burton paid an amazingly low price of only $37,000.00 for La Peregrina due to the depressed prices of that time. Side note – Ms. Taylor’s dog once got a hold of La Peregrina and the pearl had to be ‘stripped’ (gently removing the microscopic aragonite crystal layers – called platelets – that basically make up nacre). The extremely delicate and tedious procedure was done to bring the pearl back as close as possible to its original condition.

The story of the most expensive glass of wine: One of the oldest, most widely recognized and repeated pearl legends of all time involves Cleopatra, Queen of Egypt. The story goes that Cleopatra often had lavish parties to impress her guest and one guest she wanted to impress was Marc Anthony (her Roman General lover). At one of her dinner parties it is stated that she bet him she could devour the wealth of an entire country in one meal. Believing success was his, he agreed. The meal ended and Marc Anthony was certain Cleopatra had not spent the total of a country’s wealth until, to his surprise, the Queen took one very large, beautiful pearl from her earring, crushed and stirred it into her wine glass and proceeded to drink the wine along with the valuable pearl dust. Marc Anthony lost the bet and it was estimated by a roman historian in the first century (Pliny) that the now-mythical pearl’s value was equivalent to a country’s wealth – one million ounces of silver. By today’s standards this would be somewhere in the ball park of approximately $5 million! 
                           
During the Great Depression, the price of all natural pearls declined and fine, natural pearls remained devalued for decades. One such example (and lovely story!) states that Pierre Cartier (yes, that Cartier!) sold a two-strand pearl necklace in 1917 for $1 million and used the money to pay for the company’s New York headquarters. But, all things change, and it is reported that the very same Cartier necklace that had been sold for $1 million to finance the Cartier building brought only $157,000.00 at an auction in 1957. Definitely a drop in price!

Recognized by the large ‘hook’ attached to its foot and known for its tasty meat, the Queen Conch also produces rare and beautiful non-nacreous (without normal nacre) “pearls”. They are not considered true pearls by experts because they are non-nacreous and so they use the term “pearl” in quotation marks to refer to them. Another gastropod mollusk, the melo melo, also produces beautiful non-nacreous “pearls”. Melo melo “pearls” are among some of the rarest gems on earth.