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.
A gem variety of the mineral cordierite, transparent to translucent iolite can be light to deep blue, usually with a purplish tinge. Named for the Greek work for violet, iolite is known as the gemstone for clear vision.
Until the 1950s, topaz was known as a yellow to golden gemstone. Since that time, routine radiation and heat treatment of pale topaz to turn it shades of blue has made it a more appealing and more affordable gem.
An ancient gemstone, peridot has adorned jewelry pieces as long ago as the time of the time of the Pharaohs in Egypt. One of the few semiprecious gemstones found only in shades of green, peridot is the gem-quality subset of the mineral olivine, is an official birthstone for those born in the month of August.
A gem variety of crystalline quartz, citrine ranges in color from golden yellow to orange. Closely related to amethyst, sometimes the two minerals are found growing together in the same crystal. An alternate birthstone for those born in November, some wearers believe that citrine can help improve personal clarity and eliminate self-destructive tendencies.
Carnelian is a variety of semiprecious quartz with a brownish red to orange color. One of the oldest known gemstones, carnelian was prized by nobility throughout antiquity. Carnelian is believed to bring good luck to its wearer.
Most often reddish in color, garnets (rock-forming minerals with a crystal structure) are actually a family of 15 distinct minerals in colors of every shade with the exception of blue. Five are commonly used as gemstones. The most popular garnets are pyrope (usually dark red) and rhodolite (raspberry red or purplish-red). Garnet is the official birthstone for January.