Today almost all pearls are produced by a culturing process where farmers encourage pearl growth to begin and the process then continues naturally. Pearls are cultured in several species of oysters and mussels and in both saltwater and freshwater environments; this, along with the natural progression of growth, helps to explain the great variety of colours, shapes and sizes that you will encounter when looking to buy pearls. In the first of two blogs focusing on pearls this June, we explore how pearls are cultured.
Cultured pearls will be either saltwater or freshwater although somewhat confusingly, saltwater cultured pearls are often referred to as simply cultured. These are grown in various species of oyster, each found in a specific region and producing varying sizes and colours; including the coveted large South Sea and the famous black Tahitian. Some of the oysters used in pearl production are quite large, such as the Pinctada Maxima that produces South Sea pearls in average sizes of around 13mm, while others are smaller: Akoya pearls are grown in several different smaller species and rarely exceed 10mm. Each oyster can yield only a single pearl during a growth cycle that can take a couple of years; while some may be used a second time, the quality of pearl is usually lower in oysters that have been used before.
To encourage the oyster to grow a pearl, a small piece of tissue from another oyster is inserted, often along with a bead which promotes (although by no means guarantees!) a spherical shape. This requires a very precise surgical procedure and is a delicate job. Once complete, the oyster is returned to the sea, attached to a frame, and the farmer must hope for the best. Aside from cleaning the frames and keeping them free from debris there is little they can do to assist the oyster in its task. Pearl farms are vulnerable to climate alterations which can cause lack of food for the oysters or outbreaks of disease, and extreme weather such as typhoons which can obliterate entire productions. This can be devastating since it takes time for new oysters to grow to maturity and go on to produce pearls: there is significant initial cost and a long wait for income. Even assuming conditions remain favourable you are not guaranteed a beautiful pearl at the end: the quality can vary considerably and many of the pearls will be misshapen, ridged, spotted or unattractive in colour.
Freshwater pearls are grown in mussels and generally do not grow so big as their largest saltwater counterparts, although larger sizes have been produced in recent years. Each mussel can often produce several pearls at once, although the number depends on the size of pearl. Unlike saltwater, freshwater cultured pearls do not typically contain a bead (although the use of beads in freshwater pearls is increasing); only the tissue implant being used to stimulate the mussel to produce a pearl. Traditionally the quality of freshwater pearls has not been so high as saltwater but that has been changing. Improvements in culturing techniques have led to a gradual increase in the roundness, smoothness and lustre of freshwater pearls, which can sometimes be very difficult to distinguish form their saltwater counterparts.
If you'd like to know more about pearls or are looking to purchase a piece of pearl jewellery then our experienced team of jewellers and gemmologists are here to help. A selection of our pearl jewellery is available to view online but we have a much wider range in our showroom.