Ratnapura, town, southwestern Sri Lanka. It is situated southeast of Colombo, on the Kalu River. Dominating the town is a hill on which the Portuguese built a fort. Ratnapura (Sinhalese: “City of Gems”) is Sri Lanka’s chief source of precious and semiprecious stones (including rubies, sapphires, and cat’s-eyes), which are found in the valleys around the town and are prepared by Muslim gem cutters; examples are on display in the town’s gem museum. Graphite is also mined in the area. The town is connected with Colombo by rail and with other parts of Sri Lanka by road. Pop. (2007 est.) 48,412.