sentences:  Some of the diamond finishers were technically gifted and strove to improve the tools used for working diamonds.The "Pfälzer Doppen", also called the "Amann-Doppen", a kind of dop developed and patented by Philipp Amann in 1928 that is still used today, was best at meeting the demands of the trade and became the standard everywhere.In all the world's countries in which diamonds are cut and polished, machines from the firm Amann are in use.