Amethyst is the purple variety of quartz and is a popular gemstone.

Purple has long been considered a royal color so it is not surprising that amethyst has been so much in demand during history. Amethyst has been popular as a gem since Pre-Roman times. The Greek work "amethystos" basically can be translated as "not drunken." Amethyst was considered to be a strong antidote against drunkenness, which is why wine goblets were often carved from it! While medieval European soldiers wore amethyst amulets as protection in battle.  Fine amethysts are featured in the British Crown Jewels and were also a favorite of Catherine the Great and Egyptian royalty. Amethyst, transparent purple quartz is the most important quartz variety used in jewelry.

Leonardo Da Vinci wrote that amethyst was able to dissipate evil thoughts and quicken the intelligence.

Because amethyst was thought to encourage celibacy and symbolize piety, amethyst was very important in the ornamentation of Catholic and other churches in the Middle Ages. It was, in particular, considered to be the stone of bishops and they still often wear amethyst rings.

In Tibet, amethyst is considered to be sacred to Buddha and rosaries are often fashioned from it. The legend of the origin of amethyst comes from Greek myths. Dionysius, the god of intoxication, was angered one day by an insult from a mere mortal and swore revenge on the next mortal that crossed his path, creating fierce tigers to carry out his wish. Along came unsuspecting Amethyst, a beautiful young maiden on her way to pay tribute to the goddess Diana. Diana turned Amethyst into a stature of pure crystalline quartz to protect her from the brutal claws. Dionysus wept tears of wine in remorse for his action at the sight of the beautiful statue. The god's tears stained the quartz purple, creating the gem we know today.

Amethyst is actually a form of Quartz - one of the most common substances on earth. Tiny amounts of iron and aluminum turn ordinary clear quartz into amethyst. All forms of quartz (including amethyst) are piezoelectric, making for important applications in electronics. Tourmaline is the only other gemstone that possesses this property.

Amethyst ranges from pale to dark violet. The finest qualities of amethyst are a medium dark violet with a strong secondary red color. Darker shades of amethyst may display slight color fluctuations under different light sources.

Amethyst is not the same everywhere. Different localities can produce a unique amethyst to that particular region or even to that particular mine. Experts can often identify the source mine that a particular amethyst came from. The key to this is the specimen's color, shape of crystal, inclusions, and associations and character of formation.

The following is a list of many of the more noteworthy localities and some of the attributes that characterize the amethyst found there.

• Vera Cruz, Mexico -- very pale, clear, prismatic crystals that are sometimes double terminated and has grown on a light colored host rock. Crystals are typically phantomed, having a clear quartz interior and an amethyst exterior. Some are sceptered and phantomed.

• Guerrero, Mexico -- dark, deep purple, prismatic crystals that radiate outward from a common attachment point. Often the crystals are phantomed opposite of Vera Cruz amethyst having a purple interior with a clear or white quartz exterior. These are some of the most valuable amethysts in the world.

• Minas Gerais and Rio Grande do Sul, Bahaia, Brazil -- crystals form in druzy crusts that line the inside of sometimes large volcanic rock pockets or "vugs". Some of the vugs form from trees that were engulfed in a lava flow millions of years ago and have since withered away. Other vugs are just gas bubbles in the lava. Some vugs can be quite large. The crystals that form is usually light to medium in color and only colored at the tops of the crystals. Most clusters form with gray, white and blue agate and have a green exterior on the vugs. Calcite sometimes is associated and inclusions of cacoxenite are common.

• Maraba, Brazil -- large crystals with unattractive surfaces that are of a pale to medium color and often carved or cut into slices.

• Thunder Bay, Canada -- a distinct red hematite inclusion just below the surface of the crystals is unique to this locality. Clusters are druzy crusts that line the fissures formed in ancient metamorphic rocks.

• Uruguay -- crystals are dark to medium and form in druzy crusts that line the inside of volcanic vugs that have a gray or brown exterior. The crystals are usually colored throughout, unlike the Brazilian crystals, and form with a multicolored agate that often contains reds, yellows and oranges. Often amethyst- coated stalactites and other unusual formations occur inside these vugs.

• Africa -- crystals are usually large but not attractive. However, the interior color and clarity are excellent and polished slices and carvings as well as many gemstones are prized and admired.

• Maine, USA -- Dark druzy clusters that are not widely distributed today.

• North Carolina, USA -- Druzy clusters that have a bluish-violet tint.

• Pennsylvania, USA -- druzy clusters that filled fractures in metamorphic rocks. They are generally a brownish purple and patchy in color.

• Colorado, USA -- druzy clusters form crusts inside of fissures in sandstone, often on top of a crust of green fluorite. Crystals are dark but rather small.

• Italy -- both Vera Cruz like crystals, although not as well defined, and large parallel growth clusters with good evenly distributed color.

• Germany -- associated with colorful agates that form a druzy light-colored crust.

• Ural Mountains, Russia -- a very clear and dark variety that is cut for fine expensive gemstones, natural uncut clusters are rarely on the market.

Amethyst is only one of several quartz varieties. Other varieties that form macroscopic (large enough to see) crystals are as follows:

• Citrine is a yellow to orange gemstone variety that is rare in nature but is often created by heating Amethyst.

• Milky Quartz is the cloudy white variety.

• Rock crystal is the clear variety that is also used as a gemstone.

• Rose quartz is a pink to reddish pink variety.

• Smoky quartz is the brown to gray variety.