High Quality Content by WIKIPEDIA articles! HMS Amethyst was a Modified Black Swan-class sloop of the Royal Navy. She was laid down by Alexander Stephens and Sons of Linthouse, Govan Scotland on 25 March 1942, launched on 7 May 1943 and commissioned on 2 November 1943, with the pennant number U16. After World War II she was modified and redesignated as a frigate, and renumbered F116.