Amethyst

Amethyst is one of the accepted gemstones for the month of February as well as the 6th year Wedding Anniversary gemstone.  It can range in color from light purple to a deep dark purple.  It comes in all different sizes from tiny stones to giant geodes weighing hundreds of pounds.  Amethyst's sister stone is the Citrine.  Sometimes, Mother Nature mixes Citrine and Amethyst together into the same gem.  When this occurs it is called Ametrine.

Brazil is the primary source for this gem, however it is also found in large quantities in Zambia as well as other locales.

In ancient times, Amethyst was thought to have protective powers against the intoxicating effects of alcohol.
It was also used to heal addictions.  It was sought after as a cure for hearing disorders, insomnia and headaches and other pains.  It was also suggested in ancient times that a person suffering from a mental illness could wear an Amethyst around his neck to stabalize his condition.

Amethyst was the stone of royalty because of its purple color and was prized by kings and queens throughout the ancient world.

Gemstone Specifics

Amethyst belongs to the Quartz family and must be purple in color to be called Amethyst.  Amethyst occurs as 6 sided crystals in its natural form as well as the drusy form (many tiny crystalline structures forming something akin to a "crust" over a matrix stone)  Amethyst derives is beautiful color from the presence of manganese, however it is the amount of iron within the quartz crystal that produces the depth of the purple color.

Amethyst is a hard stone and is a very good choice for jewelry use as it will stand up well to wear.
It has a hardness of 7 on the MOH's scale.  Amethyst is quite affordable and can be found in large carat weights. 
The majority of Amethyst on the market today are heat treated to achieve a deeper color.   Heat treatment is permanent and will not fade.