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.
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 help maintain calm and composure.
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.