A copper plaque used by Dutch master Harmen Rembrandt van Rijn for one of his engravings and discovered at the back of a 17th Century painting was sold for £ 210,500 (US $ 350,800) on June 26 th 1997 by Christie's London. Dating from 1656, the copper plaque was engraved by Rembrandt for a print of Abraham surrounded by angels. It was discovered at the back of a painting by the 17th Century Flemish artist Peter Gysels bought some 50 years in a small Yorkshire antique shop and now worth about US $ 15,000.