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 (1799) HMS Amethyst (1799) HMS "Amethyst" was a Royal Navy 36-gun "Penelope"-class fifth-rate frigate, launched in 1799 at Deptford. "Amethyst" served in the French Revolutionary Wars and the Napoleonic Wars, capturing several prizes. She also participated in two boat actions and two ship actions that won her crew clasps to the Naval General Service Medal. She was broken up in 1811 after suffering severe damage in a storm. "Amethyst" was commissioned in May 1799 under the command of Captain John Cooke. She then operated on the Dutch coast later that year. During the Anglo-Russian invasion of Holland, "Amethyst" conveyed the Duke