People have used mother-of-pearl for adornment since pre-historic times. In more recent centuries it also turned up in marquetry, gaming chips, devotional objects and, as a bead, in the cultured pearl industry. It was also the raw material of the button trade, hugely popular until plastics took over. Mother-of-pearl is the smooth, iridescent nacre that lines the inside of certain mollusc shells. Pinctada maxima, the Australian South Sea pearl oyster (also called the pearl button oyster and mother-of-pearl oyster), has been an important source, both for the quality of its nacre and for the sheer size of its wild shells, which average 20 to 30 cm and reach 40 cm in exceptional cases. Local shells in the north had been gathered since pre-history, but Australia's pearling industry proper began in 1868, centred on Queensland. In the photos, a pearl shell sorter on Thursday Island, Queensland, Australia. Photo Frank Hurley © National Library of Australia; and a series of Pinctada maxima shells being worked into buttons, from the Museum of Applied Arts and Sciences collection (B&W picture from 1933 at the Pearlbutton Manufacturing Co. Ltd in Sydney, New South Wales, Australia).

Source: Rui Galopim de Carvalho (Portugal Gemas Academy)