Amethyst - Amethyst is a form of quartz, composed of silicon dioxide which is the primary ingredient of sand. Most quartz samples are clear, but amethyst has a beautiful purple color due to small amounts of iron impurities in the crystal lattice. Amethyst is the birthstone for February and the Aquarius zodiac sign.
Aquamarine - Aquamarine is a gemstone that is a member of the beryl family of stones. The name means "sea water" and serves as an accurate description of the gemstone's color. Aquamarine is the birthstone for March and the Pisces zodiac sign.
Diamond - Diamonds are perhaps the most cherished of all gemstones. The tertiary carbon structure of diamonds is responsible for the extreme hardness of this mineral, which has a name derived from the Greek work adamas, meaning unconquerable. There is evidence that diamonds were formed many millions of years ago deep within the earth at very high pressures. Diamond is the birthstone for April and the Aries zodiac sign.
Emerald - Emerald is another gemstone that is a variety of beryl (along with aquamarine), this time with a beautiful green color. The world's finest emeralds originate in Colombia, a country that is also famous for it's coffee and coca plants. Emerald is the birthstone for May and the Taurus zodiac sign.
Garnet - Garnet is the name of a large family of gemstones that includes pyrope, grossular, andradite, spessartine, and almandine. Although they are all classified as gemstones, the almandine and pyrope families are the most precious and most widely used for this purpose. Garnets display a wide spectrum of chemical compositions and therefore are found in a variety of colors with the exception of blue. Garnet is the birthstone for January and the Capricorn zodiac sign.
Opal - Opal is one of the few non-crystalline gems that has a very poorly defined system and a relative hardness far less than quartz. Opal is mined in a number of countries with Australia being the top provider of both black and white opals. Opal is the birthstone for October and the Libra zodiac sign.
Pearl - Pearl is one of the gems derived from animals and plants and is described as "organic" even though pearls are composed primarily of the salt calcium carbonate. Other members of this class include coral, amber, and jet. Pearl is the birthstone for June and the Gemini zodiac sign.
Peridot - Peridot is a gemstone variety of the mineral olivine, a silicate formed with magnesium and iron and commonly found amongst basalts (lava rock). The crystal system is orthorhombic with a hardness slightly less than quartz. Peridot is the birthstone for August and the Leo zodiac sign.
Ruby - Ruby is a term for the red gemstones derived from the mineral corundum, formed primarily from aluminum oxide. Pure corundum is a colorless, trigonal crystal with a hardness between that of emerald and diamond. Trace amounts of chromium are what gives the ruby its rich red color. Ruby is the birthstone for July and the Cancer zodiac sign.
Sapphire - Sapphire is another gemstone associated with the corundum class of minerals (along with ruby), where the presence of trace impurities of iron and titanium are responsible for the deep blue color. Several other colors of corundum are classified as sapphire such as yellow and pink. Sapphire is the birthstone for September and the Virgo zodiac sign.
Topaz - Topaz is commonly found in gravel as rounded pellets, the result of being worn down by water and sand for thousands of years. The mineral is a silicate of aluminum containing about 20 percent water and fluorine. The relative proportions of these impurities are responsible for the color of the stones. Topaz is the birthstone for November and the Scorpio zodiac sign.
Turquoise - Turquoise is a member of the microcrystalline minerals (along with jade and lapis) that have been used in stone carvings for thousands of years. This mineral occurs as nodules and veins that are either blue or green in color, although the name Turquoise is itself considered the name for a shade of color that is greenish-blue. Turquoise is the birthstone for December and the Sagittarius zodiac sign.