Coster Diamonds is one of the oldest still operational diamond factories in Amsterdam. It was founded back in 1840 and now offers visitors the chance to see their craftsmen at work cuttin and polishing diamonds. As well as running tours, Coster Diamonds hosts a large collection of both lose and set diamonds in the showrooms, including some weighing over 1 carat. Coster Diamonds sell a range of jewellery including rings, earrings, bracelets, watches and pendants.