One of the oldest known gems, turquoise has been prized for thousands of years. The Egyptians believed it had powerful mystical properties, and turquoise jewelry has been found interred with 7,500-year-old mummies. Ancient manuscripts from Persia, India, Afghanistan and Arabia say that the health of a person wearing turquoise could be assessed by variations in the color of the stone. Montezuma’s treasure, now displayed in the British Museum, includes a carved serpent covered by a mosaic of turquoise.

Turquoise was especially revered by the Native American culture, an association that dates back to the Aztec empire more than 700 years ago. For the Aztecs, turquoise was reserved for the gods and mere mortals were forbidden to wear it. They believed it to be a gem of good fortune and a commodity more valuable than gold. Native Americans believed turquoise protected people from demons and they even placed turquoise in tombs to guard the dead. The stone’s colors were thought to be symbolically blue for the heavens and green for the earth. Often warriors tied turquoise to their bows to ensure accurate shots.

Today, turquoise is still believed to provide protection and bring luck. It is said to also promote prosperity, love, healing, courage and friendship. The stone is thought to relax the mind and ease mental tension.

The gem’s opaque turquoise color varies from shades of greenish blue to deep cobalt to sky blue. Some varieties display white or brown matrixes, which are streaks of the mother stone from which they came, while others have veins of color called “spiderwebs” running through them. Generally, the bluer the blue, the more highly valued the stone. A clear, even texture without mottling or veins is also preferred. The most rare and valuable color is an intense azure, but the most common is the mild to medium sky blue. Sometimes imitated by minerals such as chrysocolla, turquoise stones are often dyed or colored with coatings of various resins.

In the 13th century, turquoise was mistakenly believed to have come from the country of Turkey. Hence, its name came from the French word for Turkey, “Turquie.” The stone was actually brought to Europe from Persia (now Iran), via Turkey. It is a mineral usually found in association with copper deposits and is sometimes mined as a by-product of copper mining.

Although turquoise is found in desert regions worldwide, the finest and most valuable comes from Iran. Iranian turquoise is a pure robin’s egg blue that is free of green overtones, matrix or black veins. Perhaps the most famous turquoise today, however, comes from the southwestern United States. The occurrence in Arizona and New Mexico produces greener shades of the stone with matrix streaks of various colors.

While only ranking between 5.0 and 6.0 on the Mohs Scale of hardness, turquoise remains quite popular for jewelry. In Europe, turquoise rings are given as forget-me-not gifts, while in the United States, the stone is given as traditional 5th and 11th wedding anniversary gifts. It has even become a modern consideration for the December birthstone. When wearing turquoise over the years, the stone will absorb oil from a person’s skin, causing a slight change to the color of turquoise.

Marcasite, a name derived from the Arabic word for pyrite, is the term applied to small polished and faceted stones inlayed in sterling silver. Their color is usually described is being pale bronze, looking rather gray with a greenish tint. A multi-colored tarnish may exist as a result of oxidation. With a metallic luster and opaque crystals, marcasite ranks 6.0-6.5 on the Mohs Scale. Occurrences are worldwide, especially in the United States, Mexico, France, Peru, China and Russia.