Turquoise comes in many shades of green to blue and has varying degrees of matrix or veining in it.  The matrix can range from a very faint gray all the way to a deep black.  Turquoise is perhaps the oldest of gemstones known to humanity and was typically reserved for kings and warriors.  It is a protective stone and has many healing powers.  It is the birthstone for the month of December and is recognized as a stone associated with the Zodiac signs of Aquarius, Pisces, Sagittarius, and Scorpio.