The most valuable gem variety of crystalline quartz, amethyst ranges in color from pale lilac to deep reddish purple. The official birthstone for those born in February, amethyst is said to guard against drunkenness.
One of several gem-quality varieties of beryl, aquamarine is sought for its breathtaking sea-blue colors and its wonderful transparency and clarity. The official birthstone for those born in March, aquamarine is believed to impart foresight, courage, and happiness.
The gem variety of crystalline quartz, citrine ranges in color from golden yellow to orange. An alternate birthstone for those born in November, citrine is said to improve personal clarity and eliminate self-destructive tendencies.
One of the most abundant minerals in the earth's crust, quartz displays the greatest profusion of colors, patterns, and textures of any mineral. Gems cut from individual quartz crystals include amethyst, smoky quartz, rock crystal, citrine, and rose quartz. Finely grained quartz, which ranges from translucent to opaque, is typically carved or cut as cabochons or beads.
The most colorful of all gemstones, tourmaline is in fact a family of 14 different minerals. Best known in shades of green and red, it occurs in every color from colorless to black, or as a single stone with several distinct colors. Tourmaline is the traditional birthstone for the zodiac sign of Leo.