Pottery & Porcelain Marks – Words & Initials –R: Roseville Pottery Co., the most popular art pottery with collectors, made dinnerware, kitchenware, and decorative items. The company, from Roseville and later Zanesville, Ohio, used many different marks. But beware, the name Roseville was used by other potteries in Roseville, Ohio. The "R.S." marks were used by potteries owned by members of the Schlegelmilch family known for their porcelain and figurines during the 19th and 20th centuries. Watch out for marks saying "Schlegelmilch" that were used by Oscar, Erdmann, and Reinhold.