From Hancocks of London: From the start Dusausoy sold both jewellery by their own design, and antiques. 1889 The Dusausoy mark was registered by Mrs. Dusausoy, it included the initials ‘PD’ and a symbol of two stars. It was registered at the Rue Beaurepaire. 1905 Dusausoy began to deal gemstones. 1912 Mme Dusausoy’s son, Justin, registered his own mark in April, the initials ‘JD’ with a diamond shape. They advertised the valuation, modification and improvement of antique pieces, and specialised in re-mounting old stones at their 41, Boulevard des Capucines workshop in Paris. Justin was assisted by his son who managed some of the business dealings and also designed some pieces. Pierre, Jean’s... more.