Six ships of the Royal Navy have been named HMS Amethyst, whilst another was planned:

• HMS Amethyst (1793) was a 36-gun fifth-rate frigate, originally the French frigate Perle, launched in 1790, captured in 1793, and wrecked off Alderney in 1795.
• HMS Amethyst (1799) was a Penelope-class 36-gun fifth rate launched in 1799 and wrecked in 1811.
• HMS Amethyst (1844) was a Spartan-class 26-gun sixth rate launched in 1844 and sold in 1869 for use as a cable vessel.
• HMS Amethyst (1873) was an Amethyst-class screw corvette launched in 1873 and sold in 1887.
• HMS Amethyst (1903) was a Topaze-class cruiser launched in 1903 and scrapped in 1920.
• HMS Amethyst (F116) was a modified Black Swan-class sloop launched in 1943. She was later designated as a frigate, was involved in the Yangtze Incident in 1949 and was broken up in 1957.
• HMS Amethyst was to have been a River-class minesweeper. She was renamed HMS Waveney before being launched in 1983, and was sold to the Bangladeshi Navy in 1994, being renamed Shapla.

Ships named Amethyst have earned the following battle honours:

• Cerbere, 1800
• Thetis, 1808
• Niemen, 1809
• China, 1856−60
• Ashantee, 1873−74
• Heligoland, 1914
• Dardanelles, 1915
• Atlantic, 1945
• Korea, 1951−52

• HMT Amethyst (T12) was an anti-submarine trawler requisitioned in 1935 and sunk by a mine on 24 November 1940.
• Amethyst was the Royal Navy's bridge simulator in the 1990s at HMS Dryad, named after the Black Swan-class HMS Amethyst.

• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.
• Hepper, David J. (1994) British Warship Losses in the Age of Sail, 1650-1859. (Rotherfield: Jean Boudriot). ISBN 0-948864-30-3
• Winfield, Rif (2008). British Warships in the Age of Sail 1793–1817: Design, Construction, Careers and Fates. Seaforth. ISBN 978-1-86176-246-7.