Amethyst is not primarily defined by carat weight; this is different to most gemstones where the carat weight exponentially increases the value of the stone. The biggest factor in the value of amethyst is the color displayed. The highest grade amethyst (called "Deep Russian") is exceptionally rare and therefore, when one is found, its value is dependent on the demand of collectors. It is, however, still orders of magnitude lower than the highest grade sapphires or rubies (padparadscha sapphire or "pigeon's blood" ruby). Amethyst Amethyst is a violet variety of quartz. The name comes from the Koine Greek ἀμέθυστος "amethystos" from
Amethyst Incident largely based on the events of the Yangtze incident. Richard Todd starred as Kerans in the 1957 film "Yangtse Incident: The Story of HMS Amethyst" (in the US most commonly released as "Battle Hell", but also as "Escape of the Amethyst" and "Their Greatest Glory"). For the film, "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 Incident The "Amethyst" Incident, also known as the Yangtze Incident, was a historic event which involved the Royal Navy ship HMS "Amethyst" on