Amethyst even if the iron concentration is low. Natural amethyst is dichroic in reddish violet and bluish violet, but when heated, turns yellow-orange, yellow-brown, or dark brownish and may resemble citrine, but loses its dichroism, unlike genuine citrine. When partially heated, amethyst can result in ametrine. Amethyst can fade in tone if overexposed to light sources and can be artificially darkened with adequate irradiation. Amethyst was used as a gemstone by the ancient Egyptians and was largely employed in antiquity for intaglio engraved gems. The largest Ancient Egyptian amethyst mines are located at Wadi el-Hudi and those mines may be the
HMS Amethyst (F116) escaped under cover of darkness. For the 1957 film "Yangtse Incident: The Story of HMS Amethyst", "Amethyst" was brought out of storage to play herself. As her engines were no longer operational, her sister ship, , was used for shots of the ship moving. "Amethyst" was scrapped shortly after the filming was finished. HMS Amethyst (F116) HMS "Amethyst" was a modified "Black Swan"-class sloop of the Royal Navy. 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