Colour in cultured pearls has many causes, namely organic pigments and the chemistry related to the water reservoir where the pearl shell is grown (for example, sea water and freshwater have different manganese concentrations with impact on the color of the nacre). The pearl mollusc species is, of course, one of the most important factors in this process, specially the donor specimen that provides the mantle tissue graft (known as saibo) that is inserted in the gonads or mantle (depending on the culturing method) of a productive pearl mollusc for the formation of the cultured pearl sac. Experiments in xenotransplantation (meaning graft from one species in host mollusc of another species) have demonstrated that colour is controlled mostly by the genetic characteristics of the graft in cultured pearls.
Furthermore, understanding colour mechanisms is critical in the laboratory to determine if the colour of a pearl is natural or a resulto or a treatment (e.g. dyeing, heat, bleaching).  The pearl oyster Pinctada margaritifera typica has mantle tissue cells that secrete unusual earthy coloured nacre (seen in the oysters' mother-of-pearl shell interior), and thus the colours of those cultured pearls are also expected to be coloured in such a way. 
#southseapearls #tahiti #indonesia #myanmar #pearls #culturedpearls #australia

Mother-of-pearl has been used in decoration since pre-history as consequence of the capture of molluscs for food. In the modern ages, it became artistically used in marquetry, gaming chips, devotional artefacts, as a bead for the cultured pearl industry but also in the button industry. As buttons, it was rather popular before plastics came into action. Mother-of-pearl is the smooth nacreous iridescent coating on the interior of some molluscs and Pinctada maxima, the Australian South Sea pearl oyster (also known as pearl button oyster and mother-of-pearl oyster) has been a rather important source not only for the quality of the nacre but also because the wild shells have notorious sizes averaging between 20 and 30 cm up to 40 cm in exceptional cases. Although local shells in the north have been collected since pre-history, the pearling industry only started in Australia in 1868, especially in Queensland.
In the photos, a pearl shell sorter in Thursday Island, Queensland, Australia. Photo Frank Hurley © National Library of Australia ; and a series of Pinctada maxima shells being manufactured as buttons, from the ‪Museum of Applied Arts and Sciences‬ collection (B&W picture from 1933 at the The Pearlbutton Manufacturing Co. Ltd in Sydney, New South Wales, Australia).

#southseapearls 

 

The art deco piece was famously worn by Margaret for her 19th birthday photograph taken by celebrated photographer Cecil Beaton in 1949.

It was bought by an undisclosed private bidder for £396,800, including buyer's premium, during the sale at auction firm Dix Noonan Webb's Mayfair saleroom in central London. 

Frances Noble, the company's associate director and head of the jewellery department, said of the sale price: 'It not only reflects the strength of the current auction market but also the overriding importance of provenance.

'Princess Margaret was photographed wearing this bracelet on numerous occasions which certainly added to the appeal of the piece, attracting international interest and extremely competitive bidding - an exceptional result for the vendor.'

 

Colour in cultured pearls has many causes, namely organic pigments and the chemistry related to the water reservoir where the pearl shell is grown (sea water and freshwater have different manganese (Mn) concentrations with impact on nacre's colours). The pearl mollusc species is, of course, one of the most important factors in this process, specially the donor specimen that provides the mantle tissue that is inserted in the gonads or mantle (depending on the culturing method) of a productive pearl mollusc for the formation of the cultured pearl sac. Understanding colour mechanisms is critical in the laboratory to determine if the colour of a pearl is natural or a resulto or a treatment (e.g. dyeing, heat, bleaching).