Several ships of the Royal Navy have been named HMS Amethyst:
- Amethyst , launched in 1844, was a Spartan-class sixth-rate sail warship.
- Amethyst , launched in 1873, was the lead ship of her class of wooden screw corvettes.
- Amethyst , launched in 1903, was a Topaze-class third-class cruiser . In World War I, she fought at the battles of Heligoland Bight and Dardanelles. She was scrapped in 1920.
- Amethyst (T12) , commissioned in 1935, was an anti-submarine trawler. She was sunk by a mine on 24 November 1940.
- Amethyst (U16), launched in 1943, was a modified Black Swan-class sloop. She served in World War II and in 1949 came under fire from the Chinese People's Liberation Army on the Yangtze River.
