Jasper has been by far the most avidly collected of all Wedgwood wares from the 18th century until the present day. It is still the style by which the firm is throughout the world and it continues to be produced in the 1990S. A dense white stoneware, jasper was the outstanding invention of Josiah Wedgwood's career as a potter - and the most significant innovation in ceramics since the discovery of porcelain by the Chinese some 900 years earlier.