Historically, the world's best pearls came from the Persian Gulf, especially around what is now Bahrain. The pearls of the Persian Gulf were naturally created, and collected by breath-hold divers. The secret to the special luster of Gulf pearls probably derived from the unique mixture of sweet and salt water around the island. 

Unfortunately, The natural pearl industry of the Persian Gulf ended abruptly in the early 1930's with the discovery of large deposits of oil. Those who once dove for pearls sought prosperity in the economic boom ushered in by the oil industry. The water pollution resulting from spilled oil and indiscriminate over-fishing of oysters essentially ruined the once pristine pearl producing waters of the Gulf. Today, pearl diving is practiced only as a hobby. Still, Bahrain remains one of the foremost trading centers for high quality pearls. In fact, cultured pearls are banned from the Bahrain pearl market, in an effort to preserve the location's heritage. 

The largest stock of natural pearls probably resides in India. Ironically, much of India's stock of natural pearls came originally from Bahrain. Unlike Bahrain, which has essentially lost its pearl resource, traditional pearl fishing is still practiced on a small scale in India.

The art of culturing pearls was invented in Japan in 1893 by a man named Kokichi Mikimoto. He discovered that by introducing a tiny bead of mother-of-pearl (the white substance on the inside of a mussel's shell) into an oyster, that oyster would began to cover the irritant with nacre (the secreted substance that makes up a pearl). 

Interestingly, one of the first places to begin farming cultured pearls outside of Japan was near the Gulf of California in Mexico. Unfortunately, Mexican pearls disappeared from the international markets when over fishing of natural pearl oyster banks took its toll and the Mexican government had to impose a No-Fishing law in the late 1940's. Mexico is today attempting to return to the pearl market with cultured half-pearls (meaning they are only pearl slices or hemispheres, not round). 

Pearls predominately come from Japan, Australia, Indonesia, Myanmar, China, India, Philippines, and Tahiti. Japan however, controls roughly 80% of the world pearl market, with Australia and China coming in second and third, respectively. The South Sea waters around Australia, Indonesia, and Myanmar are renowned for their large, white pearls, while Japan's pearls are highly valued for their lustrous character. 

Freshwater pearls constitute the bulk of China's pearl efforts. And as mentioned earlier, India is recognized as one of the last producers and handlers of naturally occurring pearls. Interestingly, although Australia's pearls derive from the same sea as those from Indonesia and Myanmar, Australia consistently advertises their pearls as distinctly superior to other South Sea pearls, emphasizing the importance of the country of origin, not simply the body of water from which they came.