The scarcity of natural pearls, makes them rare and hard to find today. Molluscs still produce natural pearls, but these underwater gifts of mother nature are discovered with far less frequency than they were years ago. However, thanks to modern pearl farming techniques, finding a beautiful pearl is no longer as difficult as it used to be.
There are basically three different types of saltwater cultured pearls: South Sea, Akoya and Tahitian. Whilst sharing similar characteristics, they can look vastly different and each pearl type comes from a different kind of Oyster. Freshwater cultured pearls are produced in a wide variety of farms, anywhere from a pond to a lake, with thousands of mussels.
Freshwater pearls are formed in mussels that live in ponds, lakes and rivers. The pearl farmer inserts a piece of donor mantle tissue directly into the mussel’s mantle which then forms a pearl made up of solid nacre, one of the reasons why freshwater pearls are so durable.
One mussel can yield up to 40 freshwater pearls from 50 implants. The growth period for freshwater cultured pearls ranges from two to six years and each mussel can be implanted up to two times.
People often think that freshwater pearls are inferior to saltwater pearls but are now finding that the best of them are comparable in quality to their saltwater counterparts.
Similar in size to Akoya cultured pearls, ranging from 2mm to 13mm (although much rarer in larger sizes). On average, most freshwater cultured pearls measure between 4mm and 7mm.
Because the vast majority of freshwater cultured pearls are nucleated with pieces of mantle tissue only, only about 2% are actually round. But because they are produced in such vast quantities, this is still a very large number.
Freshwater cultured pearls vary widely in colour, most often white or cream or natural shades of yellow, orange and purple. Some are immersed in bleach and flooded with fluorescent light and others are dyed.
|white||light cream||dark cream||yellow||orange|
Tahitian “Black” cultured pearls are not actually grown in Tahiti, but on the other islands in French Polynesia. Tahitian cultured pearls can also be grey, blue, green or brown. The most striking feature of Tahitian cultured pearls is their high price (similar to South Sea cultured pearls). Due to a combination of factors such as the larger size and unusual colours, but other factors such as the remote location of the pearl farms and the cost of maintaining the black lipped oyster population. A high quality, Tahitian cultured pearl can cost many thousands of pounds.
Most Tahitian cultured pearls measure between 8mm and 14mm. Larger size are exceptional. The value of a pearl fluctuates greatly depending on the size.
Less than half of Tahitian cultured pearls are spherical which is one reason that a whole strand of round Tahitian cultured pearls that are well matched are very expensive!.
There are three main colours associated with Tahitian cultured pearls. “Peacock” is the trade term for the colour that’s often most highly valued: a dark green to blue grey with rose or purple overtones. “Aubergine” or “eggplant”, are dark greyish purple. “Pistachio” is yellowish green to greenish yellow.
Keshi pearls are a byproducts of the culturing process and can form in both freshwater and saltwater molluscs. Keshi pearls that appear in freshwater or akoya saltwater molluscs make an affordable alternative to round pearls, although Keshi pearls that occur in South Sea and Tahitian molluscs are highly coveted and can be very expensive in comparison.
Even though unintentional, they are highly profitable for pearl farmers because they can still be made into a variety of jewellery types, from necklaces and earrings etc. and other pieces that take advantage of the interesting shapes they provide.
Keshi pearls come in a variety of colours from blue to grey to yellow and white, and it very much depends where they are farmed. Because they are made up almost entirely of nacre, they appear very lustrous and give off a shimmer of rainbow colours that appear on or just below the surface.
These are not considered real pearls as such because they are non-nacrous. But these beautiful gems come from the mollusc called a conch (KONK) snail or Strombus gigas. These rare pink “pearls” are a gem lovers delight and are very rare and desirable, made even more so because they’re entirely natural. The Conch snail is usually found in the warmer waters around Bermuda and Cuba as well as the rest of the Caribbean. The odds of finding a conch pearl are extremely low, about 1 in 10,000, with only 10 percent of these considered to be gem quality so they are a very rare catch indeed!
The usual size of conch pearls is no larger than 2-3mm in diameter and approximately 0.2 or 0.3 carats in weight. Conch pearls in sizes and quality suitable for jewellery are extremely rare.
Colours range from salmon pink, pinkish-orange, and more rarely cream, yellow and brown. The colour tends to fade over time when exposed to sun light. The surface is enriched by one quality peculiar to the conch, a structure of tiny flames in matching tones. All natural conch pearls are single pieces and consequently finding a set of matching Conch pearls definitely influences their price.
Saltwater Akoya cultured pearls are named after the Akoya oyster in which they grow. Usually farmed in protected lagoons, the akoya oysters are nucleated with a perfectly round bead made up of mother of pearl, which is carefully inserted into the oyster’s mantle tissue along with a small piece of donor mantle tissue. An Akoya pearl therefore has approximately .1 – 2mm of nacre surrounding the bead. The lustre and delicate pastel colours and perfect shape make Akoya pearls adaptable to any jewellery.
It is rare to find freshwater pearls of the same quality and lustre as the Akoya pearl, yet with modern farming techniques, there are more and more freshwater pearls of comparable quality that are just as valuable.
Akoya cultured pearls range from 2mm to 11mm in diameter.
As many as 80 percent of cultured Akoya pearls are round and near round with the rest containing shapes like baroques and semi baroques and occasionally, drops.
Processors bleach almost all akoyas after they purchase them from the farmers. They usually use hydrogen peroxide. The bleaching process, which cleans and brightens the akoyas, is carefully monitored and can take 2 weeks to 6 months to complete (better quality pearls take less time.) The characteristic white, cream, and pink hues become apparent only after post harvest processing which might include tinting to highlight body colours.
The South Seas lie between the northern coast of Australia and southern coast of SE Asia. The natural habitat of the Pinctada Maxima, one of the largest oysters used by farmers to culture pearls. Found in the warm waters of Indonesia, Australia, Philippines, Burma and Thailand, one of the characteristics that sets South Sea cultured pearls apart is their large size.
Cultured South Sea pearls range in size from 9mm to 20mm in diameter, with the majority around 13mm. Because the oysters are large, they can be inserted with larger beads than the smaller akoya oysters, and the oyster also deposits nacre faster, especially in warm waters.
Typically, around 70-90% of south sea pearls are mostly oval, button or drop pearl shaped with Baroque and Semi-baroque being quite common also. Only around 10-30% of the harvest will be round or near-round pearls. It would not be uncommon to sort through thousands of specimens in order to match just one pair of gem-quality cultured pearls.
The thick nacre of south sea pearls produces a soft glow rather than a metallic sheen. The silver-lipped variety of Pinctada maxima produces predominately white to silver pearls that can have pink, blue or green overtones. The gold-lipped variety of oyster produces pearls that range mostly from yellow to yellowish orange (called “golden” in the trade.). The neutrals and near neutrals (white, cream, and silver) account for about 90 percent of the production. Australian farmers do not process or treat South Sea cultured pearls in any way. After harvest, most cultured pearls are simply washed, sorted and graded. Some are processed and treated after export, however.
Another popular pearl style is the cultured mabé (MAH-bay), also known as a half pearl. The pearl is created on the inside of the shell rather than inside its tissue. Mabé pearls are grown intentionally by a technician placing a flat bottomed plastic nucleus inside the shell beneath the mantle tissue. The nucleus can be any shape but most often, round, oval or heart shaped. As the oyster grows it continually deposits nacre on the inside surface of its shell, covering the nucleus and forming a cultured “blister pearl”.
After the nucleus is coated with about 1mm of nacre, a technician harvests the blister pearl and removes the original nucleus, cleans the inside surface, fills it with a resin and seals the open end with a cap. The result is a cultured mabé pearl.
As these pearls have a unique shape with a flat back, they are particularly popular as earrings, rings or pendants and are often inexpensive. They are easily damaged, so they need to be handled with extra care!