Royal Coster Diamonds is the oldest still operating diamond polishing factory in the world. Famous for cutting and polishing renowed diamonds such as the Koh-I-Nor and the Star of the South and suppliers of diamond jewelry for many Royal Houses from all around the world. During free guided tours you can experience the ins and outs of cutting and polishing diamonds and see some of the most sparkling artifacts from our 175 years of craftsmanship.