Oysters & Pearls 101
How do oysters make pearls?
The use of pearls as jewelry can be found throughout recorded history in essentially every known civilization, including ancient Egypt and Mesopotamia. It’s not entirely clear how “natural” pearls are formed, but we do know the age-old idea of a piece of sand or other irritant initiating the growth of a pearl is a myth. The growth of a “natural” pearl is actually an extremely rare event and they can be worth 10’s of thousands of dollars. It’s estimated that these “natural” pearls represent less than 0.001% of all pearls in the world. So what makes up the other 99.999% of pearls? In 1883 Mikimoto Kōkichi after much experimentation found that a simple irritant was not sufficient, but if he also included a piece of mantel from another shell he could reliably generate a nearly perfect pearl! Mikimoto’s new technique to coax the oyster into making a pearl revolutionized the pearl industry, making these beautiful works of oyster art available to all. These pearls, initiated by man, but made by oysters are now known as “cultured” pearls.
Mikimoto Kokichi initiating the pearl culturing process -1883
Are there different kinds of pearls?
Freshwater Mullosk full of freshwater pearls.
Three primary oyster types are used to generate “cultured” pearls, freshwater mollusks, Akoya Oysters, Pinctada Oysters (Tahitian & South Sea pearls). Freshwater pearls are generated in warm freshwater, and due to the oysters high metabolism at these temperature it rapidly coats irritants with nacre (the shiny substance with gives a pearl it’s color and mirror like qualities). Due to the huge size of these mollusks, they can generate 10-20 pearls at a time, and some can be very large (10-16mm). However freshwater mollusks typically generate misshapen or oblong and dull pearls, due to their ultra rapid pearl growth rates.
Akoya Oysters & Pearls
Saltwater oysters (Akoya, & Pinctada) on the other hand, are grown in cold waters, which slow metabolism and nacre deposition, generating highly round pearls with mirror like nacre of various colors. Akoya oysters, usually only grow 1 pearl, but sometimes can grow 2 (twins). Due to their size Akoya oysters usually generate pearls ranging from 5-8mm with 8-9mm being very rare. Akoya pearls, have neutral body colors with separate color overtones. Body colors can include: white, cream, gold, pink, purple, blue and grey. But wait, that's not all, these body colors can have separate color overtones of pink, green, and silver. Akoya pearls are never naturally black – the black Akoya pearls we do find have been dyed using proprietary processes, and these beautiful dark pearls can also have their own color overtones.
An Akoya Oyster
Where are Akoya oysters farmed?
An Akoya pearl farm.
The majority of Akoya oyster farms are now located in China due to pollution of waters off the coast of Japan. However, the industry accepts that if the oyster is handled in Japan at any stage, the oyster can be considered a Japanese Akyoa oyster, even if the pearl was cultured and farmed in China. Regardless of their origin, the perfect roundness, combined with the high-luster nacre found in Akoya pearls, and their relative rarity compared to freshwater pearls, give Akoya pearls a higher perceived value. In fact, a string of high quality Akoya pearls can go for up to $10,000.
What are Tahitian & South Sea Pearls?
A Black lipped Oyster (Pinctada)
So what about the Tahitian and South Sea pearls? The Pinctada oyster family is used to grown these pearls, and the location of where they are grown gives the pearl their name. These pearls are more rare than Akoya due to their finicky nature, and fragility during farming. The black lipped Pinctada oysters generate a dark nacre, and so they are the original black pearl makers. South Sea pearls take years and years to be made and their luster is unprecedented. Due to the difficulties in culturing these oysters and the time required for farming, these oysters generate beautiful pearls with a high percieved value. Interestingly, the far more hardy Akoya oysters generate pearls with near equal mirror-like nacre and roundness, making them the most popular pearl oyster in the jewelry industry.