She was laid down by Alexander Stephen 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.

During the Second World War, Amethyst was deployed mostly on anti-submarine patrols and escort duties.

The action took place in the North Atlantic, south of Waterford, and resulted in the loss of all 49 of the U-boat's crew.

During the war Amethyst was credited, along with the sloops Starling, Peacock, Hart, and frigate Loch Craggie, with sinking the German submarine U-482 in the North Channel on 16 January 1945.

[1] On 20 April 1949, Amethyst was on her way from Shanghai to Nanking (now Nanjing) when she was fired upon by the People's Liberation Army.