Antique jewellery using organic gems: Part VI – Pearls

Pearls have been worn as jewellery for a very long time. Not as durable as many other gems, the earliest surviving pearl jewellery comes from Iran around 500 BC, then Ancient Egypt around 323-330 BC and then the Greeks and Romans. The oldest examples we see now mainly come from the Middle Ages and the Renaissance. The symbolism associated with pearls has changed over the centuries. While always associated with wealth and power, they have also been associated with purity and chastity. Any pictures of Elizabeth I of England, for instance, show her clothes covered in pearls and her wearing long magnificent ropes of pearls, symbolising a Virgin Queen. Pearls have also been associated with death, and were worn by widows and by mourners as a sign of respect. In the late 16^th and early 17^th centuries, pearls also become symbols of fertility, and paintings of pregnant women during this time show them wearing pearl jewellery and pearl decorated clothing.

Later in the 17^th century and into the 18^th century, pearls became associated with love and sentimental jewellery. In the 18^th and 19^th centuries, the price of pearls led to freshwater seed pearls becoming popular and being turned into lacy necklaces, bracelets and earrings.

Later in the 17^th century and into the 18^th century, pearls became associated with love and sentimental jewellery. In the 18^th and 19^th centuries, the price of pearls led to freshwater seed pearls becoming popular and being turned into lacy necklaces, bracelets and earrings.

Imitation pearls have been around a long time. Many of the pearls sewn onto clothing in the 15^th and 16^th centuries were imitation pearls, either made from shell or from painted glass. In the 17^th century, essence d’orient was used to coat the inside and the outside of glass beads. Essence d’orient was made by grinding the scales of the beak fish and placing them in lacquer, creating an iridescent liquid.

Pearls can be divided into three categories: natural pearls, nucleated cultured pearls and non-nucleated pearls. Natural pearls, apart from the freshwater seed pearls, are rare and expensive .Most pearls sold today are cultured pearls.  Cultured round pearls were first produced commercially by Mikimoto in the early 1920s and Japanese cultured pearls dominated the industry for the rest of the 20th century. Problems relating to water pollution, to overproduction resulting to smaller pearls, and virus attacks have led to a decline in the Japanese industry. China has started active pearl production.

Saltwater cultured pearls are created using bead nucleation. The process described here is the Akoya process developed by Mikimoto. It starts with a piece of graft tissue from the outer mantle of a Pinctada imbricate oyster, about 2.3mm square. The host oyster is wedged open and a slit is made in the gonad of the oyster under the mantle and foot. The graft tissue is placed in the slit, followed by a bead nucleus from the shell of a freshwater mussel, traditionally the Mississippi Pigtoe or Washboard. The wound is then closed by applied pressure and the wedge is removed so the oyster can close naturally while immersed in clean sea water. Then the implanted oyster is returned to holding trays and then to raft-suspended culture cages for about 4-6 weeks. The oysters are then moved to permanent cages in nutrient rich protected waters where they are left for periods of up to 4 years, but now more likely for 6 months, before harvest.

South sea cultured pearls, which are larger than Akoya pearls and have a thicker nacre, are either white (or shades of cream) or black. Australia dominates the production of white south sea pearls. The industry started I 1956 and uses a modified Akoya method of nucleation.

Non-nucleated freshwater pearls are created using tissue grafting. Tissue taken from a freshwater mussel (in China, the two mussels species used are Cristaria plicata and the Hyriosis cumingii) is implanted into a small incision made between the outer and inner mantle of the host mussel. Once inserted, the incision is closed by pressure from the flat blade of the incision knife and then rounded by manipulation. This process is repeated up to about 40 times. The grafted mussels are then temporarily housed in waters to which disinfectant has been added. Then they are placed in clear, fresh flowing water for 2 to 4 weeks before being moved to bamboo baskets or nylon netting and left for 1-3.5 years to grow. The host mussel is sacrificed to harvest the pearls.

The introduction of cultured pearls changed the style of pearl necklaces from the long strands of pearls worn by society ladies, courtesans and then actresses popular in the early 20^th century. Clothing styles changed too, and the little string of cultured pearls worn with a black dress or suit became acceptable.  More recently, the development of the south sea pearl industry has seen a return to some more flamboyant pearl necklace and earrings.

A useful history about pearls is the book ‘Pearls’ by Beatrice Chadour-Sampson (with H Bari), published 2013 V&A Publishing.