A variety of crystallised quartz occurs in colours ranging from deep purple to pale lavender. The presence of manganese in clear quartz produces amethyst, while the amount of iron content varies the strength of the purple colouration. The name derives from the Greek word amethystos, meaning remedy for drunkennessù. The Romans believed this stone prevented drunkenness and used to drink out of amethyst-encrusted goblets; some belief the effect to be the same today if amethyst is placed in a glass of wine. Amethyst is thought to bestow stability, strength and peace, to relieve stress and to calm passion, emotional violence and anger. It is a powerful healing gem, having been used in treating disorders of the nervous system, digestive tract, heart, stomach, skin and teeth. It has also been helpful in the treatment of blood disease, burns and scalds, colour blindness, infections and oedema. An amethyst under the pillow can aid sleeplessness an amethyst placed on the centre of the forehead can relieve the pain of headaches and other disorders. Amethyst is the birthstone for February, symbolising sincerity, and the zodiac gem for Pisces (19 February to 20 March).