When it comes to Pearls it can be hard to know what type of pearl you are looking for and how much the type of pearl is going to cost. There are two main categories of pearl and these are natural and cultured. Natural pearls are very expensive compared to cultured and are also much rarer. Cultured pearls are then split into a further two categories and these are seawater and freshwater pearls.
Natural pearls are formed without any human interaction. A natural pearl occurs when an irritant gets inside of an Oysters’ soft tissue in the sea. This causes the Oyster to deploy its defence mechanism of creating a coating to go around the irritant known as nacre. It makes this coating in layers until a natural pearl is created.
Natural pearls are the most expensive type of pearl this is because they are very rare due to water pollution killing the Oysters and because of Pearl divers.
Cultured Pearls are grown on farms and the irritant is planted inside to encourage the defence mechanism and therefore create a pearl. The irritant is dependant of whether it is an Oyster or a Mussel. Oysters have a bead made of mother of pearl or resin inserted into them and Mussels have a piece of mantle tissue which contains epithelial cells from a donor mussel.
Cultured Pearls are more expensive than Freshwater pearls this is because cultured pearls are grown in Oysters and Oysters can only produce one pearl at a time whereas Freshwater pearls are produced by mussels and they can produce more than one pearl at a time.
Seawater cultured pearls are grown in oysters and come in six different varieties these include, South Sea, Tahitian, Mabe, Akoya, Keshi and seed.
South Sea pearls are mainly 9-16mm in diameter however they have been known to be over 20mm in size and are mainly from Australia and the Philippines they are produced in white, silver and gold lipped oysters.
Tahitian pearls are 8-18mm in size and have a resin or mother of pearl bead inserted. Tahitian pearls are well known for their colour this is because they have a distinctive black pigment and typically produce the darker colours of pearl sometimes referred to as black, but they also come in grey and even peacock green. Tahitian pearls are the only pearls to have some sort of grading scale and the scale goes from A-D with A being the highest quality pearl this means that
Akoya pearls are 3-10mm in size and are made from a spherical resin or mother of pearl nucleus along with mantle tissue from a donor oyster. Akoya pearls are grown off of the coast of Japan and are known for their round shape and reflective luster and white colour.
Keshi Pearls are a natural pearl that occur within a cultured pearl farm or when the graft and nucleus in a cultured pearl fail to attach this means that the oyster rejects the nucleus but retains the graft tissue and this forms an almost baroque shape pearl.
Seed Pearls are very tiny pearls and are 2mm or less in size.
Freshwater pearls are produced in Mussels instead of oyster and the pearl process is triggered by the insertion of mantle tissue from a donor mussel. In general these pearls don’t have a bead nucleus this means that when you x-ray a freshwater pearl you will be able to see the layers of the pearl and also a small empty cavity in the centre of the pearl and this would have been where the irritant (mantle) would have been but has now dried up or decomposed. Similarly, to seawater pearls there are a range of different pearls that are freshwater some of these are:
Cultured River pearls are shaped like a grain of rice and have a wrinkly appearance and are sometimes known as rice crispy pearls due to their shape.
Cultured lake pearls have a smooth skin and deep lustre this makes them more appealing. They come in a range of colours as well as shapes depending on the shape of tissue that is used as the irritant, they have been previously able to make pearls that resemble the shape of a dog and a dragon.
Freshwater Seed pearls are 2mm diameter in size or less and are cultured out of muscles.