Mother of Pearl or Nacre forms in the shells of bi-valve mollusks found in salt and fresh water. These mollusks are found around the world from the Great Barrier Reef off the coast of Australia to the Gulfs of Mexico, Panama and Venezuela.
Abalone Oysters (Haliotis)
Used in trade for thousands of years Abalone oysters are found in abundance around the world. As well as being produced for their meat, they are an excellent source of highly iridescent Mother of Pearl and Pearl, ranging in beautiful colors from turquoise, green, cream and rose.
Green Abalone (Haliotis Fulgens)
Green Abalone thrives in the cold and rocky waters in the Gulf of California. They are often encrusted with small clams that adhere to their surface whose presence gives rise to the creation of blister pearls within the Abalone. Blister pearls are formed when the clams bore into the shell from the outside, the Abalone responds in defense to the intrusion by secreting layers of nacre, which coat the foreign body on the inside of the shell eventually solidifying forming natural blister pearls.
Black-Lipped Oyster (Pinctada Margaritifera)
Harvested since millennia, the black-lipped oyster, covering the widest geographical area of any known species, was the preferred color of Mother of Pearl of Indian and Persian monarchs. However, despite this oysters name the nacre is rarely pure black, instead the colors range from gray to green with blue or rose overtones. Mother of Pearl produced by Pacific black-lipped oysters is the most sought after on the world’s market today.
Silver-Lipped Oyster (Pinctada Maxima)
Sometimes referred to as the gold-lipped oyster, these giants have been harvested for their Mother of Pearl for more than a hundred years in the South Pacific. They were first cultured for its pearls in the late 1800s but only became widely distributed in the late 19th Century. Today the silver or white Mother of Pearl or Nacre produced by this oyster is the mainstay of the Australian, Japanese and Philippine cultured pearl industries.
Ayoka Oyster (Pinctada Fucata)
Japan is famous for its Ayoka pearl producing oysters, but this has only been the case since the 1920s. Before this time Japanese divers placed little value on Ayoka pearls, discarding them and keeping the Mother of Pearl, which was used as decorative inlay in jewelry and household ornamentation. By the 1950s, with new culturing techniques, Akoya Mother of Pearl and pearl had won widespread popularity and is now exported worldwide.
Ceylon Oyster (Pinctada Radiata)
From the time of antiquity up to the 1920s the Red Sea and the Persian Gulf supplied the world's demand for Mother of Pearl and pearl. The source of the majority of Mother of Pearl came from the Ceylon oyster, known as bil-bil by the fishermen of the Red Sea. The large demand almost drove this particular species to extinction but remarkably this oyster has endured the ravages of time and new techniques in cultivation have seen numbers increase.
Atlantic Oyster (Pinctada Imbricata)
Before leaving, the Queen of Spain told Christopher Columbus that Mother of Pearl and Pearl along with gold and silver were the treasures that the Spanish monarchy desired the most. When Columbus landed on the Venezuelan coast in 1498, the royal request was answered on the islands of Margarita and Cubagua. For one hundred years, the fruits of millions of Atlantic oysters from the region were shipped to Europe to satisfy the European monarchy’s desire. The fragile Atlantic oyster came close to extinction; however, commercial farming ventures in the last century have seen an increase in numbers.
La Paz Oyster (Pinctada Mazatlanica)
Before the discovery of the Pacific’s black-lipped oyster the only other Mother of Pearl that came close to the beautiful colors of the oysters of Polynesia came from the La Paz oysters in the waters of Panama and California. At one time La Paz oysters, preferring open oceanic conditions, were near extinction but recent culturing ventures in the Gulf of California are replenishing numbers and seeing a return of black pearls and Mother of Pearl to the world market.
Mabé Oyster (Pteria Penguin and Pteria Sterna)
These two species of thin-shelled oysters are the most common sources of mabé blister pearls. Mabé pearls are artificially induced or cultured, they form when a mold made of plastic is inserted between the oyster's shell, this causes the oyster to produce layers of nacre or Mother of Pearl which eventually covers the mold, the mould is then cut from the shell. These oysters occur naturally in the Red Sea, Indian Ocean, and the tropical western Pacific.
All waterborne organisms living within shells, called mollusks, have the ability to produce Mother of Pearl. However, very few mollusks with single shells, called gastropods, do so. High quality Mother of Pearl is produced by the mollusk family called bivalves, which have two-part shells.
The popular belief that Mother of Pearl and Pearl are formed as a result of a grain of sand entering a mollusks shell is false. Both Mother of Pearl (Nacre) and Pearl form when an organic irritant such as a parasite or food-particle become trapped within the mollusk, or if the mollusk is injured in some way.
Sensing the object the living organism within the mollusk secretes calcium carbonate, a derivative mineral of aragonite, and the binding protein conchiolin. These are the same substances that the animal uses to build its shell. The layers of calcium carbonate settle on the intruder, and are interspersed by the conchiolin, which acts as a kind of organic glue binding the crystals together. The regularity of the crystals, and the number of layers result in giving the Mother of Pearl (Nacre) or Pearl what is called luster.
Mother of Pearl Luster
Luster is a phenomenon used to describe the diffraction of light from the Mother of Pearl’s surface brilliance, together with its inner, deeper radiance. The radiance is the light that is reflected, not just off the surface, but also off the internal layers. A better luster is achieved if the Mother of Pearl crystals are uniform and the layers thin and numerous, letting the light diffract uninterrupted. Mother of Pearl that has a bright mirror like finish commands higher prices, whereas cheaper quality has a low luster appearing dull with a flat finish. The quality of the Mother of Pearl luster is also dependant on external factors.
Mother of Pearl is the creation of a living organism and environmental factors play a crucial role in its formation. Mother of Pearl producing mollusks cannot regulate their body temperature, and so are susceptible to changes in external conditions.
If the waters reach a high temperature of 30 degrees Celsius, as in the Pacific, the mollusks metabolism is increased and they grow faster secreting more Mother of Pearl than a mollusk who lives in colder waters. However, the layers of Mother of Pearl are thick, not as translucent and the crystal structure imperfect resulting in a duller, less lustrous Mother of Pearl. Therefore, Mother of Pearl is rarely harvested in the hotter summer months.
But when temperatures go down to 16 degrees Celsius, the mollusks metabolism is low, and produces nacre at a slower rate. These nacre layers are thinner, and the crystal structure more even, resulting in an increased translucency and better luster.
The term iridescence is often appropriated to Mother of Pearls as well as to opal. Iridescence is a general expression used when describing the presence of a rainbow effect across the surface; this is produced by the interference or diffraction of light through the gems crystal structure.
Mother of Pearl Color
Mother of Pearl, or Nacre appears in a variety of colors from white to black, and nearly every other color in between. It derives its color from three sources: genetic make-up, food and other trace metals in the water and finally to a lesser extent the depth and salt content of the water.
The mollusks genes are in part responsible for the color of the Mother of Pearl. A rainbow lipped, or black lipped oyster instinctively creates darker colors, whereas a white lipped oyster makes lighter colors.
Mollusks are filter feeders, sucking water in with their valves, extracting minute food particles from the water then ejecting the water out. Their diet consists of Phytoplankton, microscopic algae, these algae differ according to season. In the Gulf of California the blue green algae called Cyanophites are abundant in winter, but in summer a golden algae called Diatoms are more common. These different Phytoplankton provide the mollusk with materials that change the color of their Mother of Pearl.
Some trace elements are acquired from the water, such as metallic ions, that help the Mother of Pearl gain its unique coloration. Iron can give a pink color, copper a green to blue hue, magnesium a yellow coloration etc.
Mother of Pearl Care
Mother of Pearl is a hydrated gemstone, so it is essential to keep it away from direct sunlight, strong sources of heat or very dry atmospheres. If Mother of Pearl is left to dry out, its surfaces crack, and it becomes less resistant to ware and tear. Never use strong abrasives or alcohol to polish your Mother of Pearl, as this will destroy its play of color.
Store your Mother of Pearl in a dark cool place, and keep it looking its best by wiping it occasionally with a damp cloth. Wear it often; Mother of Pearl loves the bodies natural oils. The Nizams of India, famous for their pearl treasures, used to adorn their court eunuchs with pearls as their body oils kept the pearls in perfect condition…now there’s an idea!
David-john Turner has sinced written about articles on various topics from Jewelry, Silver Jewelry. This article was written for the SilverShake website, an online retailer of sterling silver jewelry at wholesale prices. See 1000’s. David-john Turner's top article generates over 27100 views. to your Favourites.