HMT Amethyst was a naval trawler requisitioned by the Admiralty prior to the Second World War.

Amethyst was built as the commercial trawler Phyllis Rosalie by Smiths Dock Company, South Bank-on-Tees and was launched on 15 January 1934.

[1] Her first owners were the Boston Deep Sea Fishing & Ice Co Ltd, based at Fleetwood.

[1] She was sold later that year to the Admiralty, who had her converted into an anti-submarine warfare trawler with the addition of ASDIC and a four-inch gun.

They classed her and a number of other trawlers as the Gem group, and the name Amethyst was selected.