There are three main categories of cultured pearls available in today’s market. These are: South Sea Fresh Water and Akoya. Each type of pearl is unique to a specific part of the world.
South Sea pearls are farmed in salt water and grown in a large oyster shell, the Pinctada maxima. They are mainly produced in Australia, Indonesia, the Philippines and French Polynesia.
So, why are they so valuable?
There are many factors that influence the high price of a South Sea pearl, including the following:
- The Pinctada maxima oyster must reach 3-4 years of age before it can be seeded to produce a pearl.
- Each oyster usually only produces a single pearl, however some oysters able to be seeded twice.
- The seeding (the placing of the nucleus/bead) of the oyster is a surgical procedure carried out by an experienced technician.
- Each single South Sea pearl takes up to 2- 3 years to grow.
- The colour of each pearl is determined by the nacre (mother of pearl) secreted by the oyster, and nature decides what the final colour hue of each pearl will be. The pearl can take on any colour from the inside of the shell of the oyster, but its final colour cannot be predicted until harvest. Because of this, it can take some time to create a strand of matched pearls.
- The pearls range in size from 8 – 22mm.
Tahitian pearls are grown in the same way as South Sea pearls, however they are grown in a black lipped oyster known as the Pinctada margaritifera. It’s the colour of the interior of the oyster that determines the colour and variety of the black and grey Tahitian pearls. Their name is derived from the general location of Tahiti, however the pearls are actually produced in the waters of French Polynesia.
- The value of these beautiful pearls is again determined by their rarity – it’s reported that less than 5% of Tahitian pearls produced are considered gem quality.
Fresh Water Pearls
Freshwater pearls are primarily farmed in China. They grow in a mussel, as opposed to the oyster of the South Sea pearl. Freshwater pearls naturally grow in the Margaritifera mussel, which can live for over 200 years, however these are now endangered. The Chinese production of freshwater pearls now occurs in a triangle shell mussel, the Hyriopsis cumingii, and the nucleus is a living piece of mantle. There are many reasons that freshwater pearls are considerably lower priced than South Sea pearls:
- A single freshwater pearl mussel is capable of producing up to 50 pearls at a time.
- The pearls are only left in the water for a maximum of 6 months.
- The pearls are often smaller in size.
- The colour of the pearls is also determined by the interior of the mussel, however many freshwater pearls are dyed after harvest to alter or enhance their colour.
Mikimoto is the most famous name associated with Akoya pearls. It is reported that the first Japanese Akoya pearl was produced in 1893, with the first spherical pearl produced in 1905 following the relentless research of Kokichi Mikimoto. Akoya pearls are salt water grown in Japan, China and now India, and commonly range in size from 6-8mm.
The oyster used to grow Akoya pearls is known as the Pinctada fucata martensii. These oysters are seeded with a round bead, made of mother of pearl, and a small piece of living tissue. This is how the predominantly round shape of Akoya pearls is achieved. There are usually only two pearls produced per oyster.
The popularity of South Sea pearls have dramatically affected the worldwide sales of Akoya pearls, however they are still popular for those seeking pearls under 8mm as this size is unavailable in the South Sea pearl cultivation.