Article Presented by:
Yvonne Mal
With the exception of Poe Konini, Poe Rava and Titian, the Cook Islands Black Pearls, Black-lipped Pearls, Black Pearls, Black South Sea Pearls, Black Tahitian Pearls, Grey Pearls, Tahitian Black Pearls, Tahitian Cultured Pearls and Tahitian Pearls are all common names used interchangeably when referring to pearls cultured in the black-lipped pearl oyster (pinctada margaritifera) or Te Ufi.
The Black-lipped Pearl Oyster
The black-lipped oyster, a nacreous secreting mollusk (mollusc), is considered indigenous to the Polynesian Islands. Today, and in all likelihood due to the pearling industry, this oyster's habitat and culturing locations extend from the warm salt waters of Asia to Baja California, to the tropic and sub-tropical waters of the West Indies. They can be found on the Pacific side of Japan; in the Cook Islands Atolls, the Tuamotu Archipelago, the Gambier Island groups of Micronesia and Polynesia, the Persian Gulf, the Indian Ocean, the Gulf of Mexico, Australia and Fiji.
The pearl oyster was hunted to near extinction during the in the 19th century for its shell's iridescent inner lining then used to create mother-of-pearl buttons. Today, this pearl oyster is more highly prized for its ability to continuously and rapidly secrete layers of nacre on to introduced irritants much like it does to smooth its shell and to thicken it against parasites; as well as its ability to nacre a palette of colors. Its mother-of-pearl (nacre) remains a source for buttons, jewelry, musical instruments, interior floors, exterior walls, doors, ceilings, countertops, etc.
Pearls (Natural vs. Cultured)
In a pearl oyster, a miniscule parasite lodged in its tissue can result in a rare, natural pearl when the oyster secretes nacre over the parasite to smooth the irritation. Highly valued as gems for their translucence, luster and delicate play of surface colors, the pearl is hard mass consisting of the same material (mother-of-pearl) as the mollusk's inner shell.
It is said that the method of culturing pearl by intentionally inserting an object within a mollusk's shell begun in 13th-century China. Today, almost all pearls used in jewelry Freshwater or Saltwater; are the by-product of this earlier pearl culturing discovery. So that the terms we use today, i.e., Tahitian Cultured Pearls," "Freshwater Cultured Pearls," "Saltwater Cultured Pearls," "Akoya Cultured Pearls," "South Sea Cultured Pearls," etc., refer to pearls created as a result of intentionally inserting an irritant in the mollusk shell to cause the secretion of nacre.
Keisha / Keshi Pearls: Rare non-nucleus pearls which form when the oyster rejects the intentional implanted irritant, but continues to secrete nacre to the area. These pearls, although consisting of only nacreous concretion, are not considered "natural pearls" since they were formed as a result of man's intervention. They are often impossible to tell apart from natural pearls.
4 Levels of Quality - Pearls
Unlike a diamond, the naked eye is used when judging the quality of harvested pearls. Each pearl is evaluated and sorted according to its size, shape and surface defects. The four levels of grades used, by a pearl producer to determine Tahitian Cultured Pearls' surface quality, are: A, B, C, and D (rejects). This pearl grading factor is also referred to as the "Tahitian System."
A Quality: The pearl has very slight or no surface defects visible to the naked eye. Any existing defects are confined to less than 10% of its surface.
B Quality: Slightly visible imperfections confined to less than 1/3 or 30% of the pearl's surface.
C Quality: Pearl's shows several visible flaws distributed over less 2/3 or 60% of its surface.
D Quality: The pearl shows visible defects on more than 2/3 or 60% of its surface. D Quality pearls are considered rejects regardless of luster.
The Infinite Colors of the Tahitian Black Pearls
Color is one of the most subjective criteria used when grading or selecting the Tahitian Black Pearls as they are rarely black. In fact, these pearls when truly and fully black in color are very rare. The term "Black Pearl" was coined for the oyster in which they are grown the Black-lipped Pearl Oyster.
Tahitian Pearls comes in a plethora of colors and exhibits a multitude of shallow to deep iridescent luster. The colors range from a single color of black, grey, green, white, silver, cream, etc., with the majority of the aforementioned colors exhibiting a multi-mix of iridescent overtones of yellows, pinks, magenta, peacock, ocean blues, violets, platinum, brown, silver-brown, to name a few, showing on the surface of the pearls.
It is not known what causes the specie of the black-lipped pearl oyster to produce a range of colors in its nacre. One may speculate, however, that environmental factors such as mineral levels in the sea water, ocean floor contamination and water temperature; the mantle used to seed the oyster and stress levels experienced during this process, plankton color and food level filtered during feeding plays a possible part in effecting the nacre color secreted by each oyster.
Sizes
Pearl sizes are commonly expressed in millimeters. Common sizes for round and semi-round Black Tahitian Pearls range from 8mm to 12mm. While sizes can reach up to 16 mm, perfectly round pearls above 13mm are an infrequent find.
Baroque pearls (drop, semi-drop and oval), being the largest amount of a farm's output, are much easier to acquire in larger sizes. Sizes of 8mm to 14mm are easier to find.
5 Common Shapes of the Tahitian Black Pearls
The pearls are sorted into five different shapes of round, semi-round, semi-baroque, ringed or circle and baroque pearls.
Round pearls can be perfect or almost-perfectly round spheres with a diameter variation rate of less than 2%.
Semi-round (off-round or near round) pearls are slightly off from being a perfect sphere and exhibit diameter variation rate of greater than 2 % but less than 5 %.
Semi-baroque pearls (drop, button, pear and oval) have at least one axis of rotation allowing it to spin on a tabletop.
Circle or ringed pearls can be any of the aforementioned shapes and are characterized by regular streaks or concave rings, perpendicular to their axis of rotation, over more than a third of the pearl's surface.
Baroque pearls do not have an axis of rotation and are of freeform shape.
About the Author:
Yvonne Mal is a Pearl Jewelry Designer and Author of articles written for Fusion Pearl. Do you need classic, yet uniquely contemporary and exotic, handcrafted Pearl Jewelry? Visit Fusion Pearl for one-of-a-kind exotic Pearl Jewelry at http://www.fusionpearl.com
