Derby ware (därˈbē) [key], English china produced at Derby since about 1750, when William Duesbury opened a pottery there. The china was close in style to contemporary Chelsea ware and Bow ware, whose factories Derby absorbed in the 1770s. It became Royal Crown Derby in 1890 by permission of Queen Victoria. It was in this ware that the government authorized reproductions of the Rhodian and Persian porcelains in the Victoria and Albert Museum for exhibiting in the provinces. Japanese Imari porcelain also was successfully reproduced. Derby ware is distinguished by delicacy of body and richness of decoration; ivory china and eggshell porcelain are among the types manufactured. There have been a score or more of Derby marks, most of which show a crown over a D, sometimes with crossed swords and six dots, the whole in blue or red.