Turquoise, one of the birthstones for December, has been prized for thousands of years due to its unique blue-to-green color.
The stone continues to come back into fashion time and time again, with shiny sky blue turquoise consistently returning as an in-trend color.
Turquoise’s color ranges from sky blue to a murky green, with the former considered far more valuable. The blue is the result of idiochromatic copper while the green is thought to be due to either iron impurities or dehydration.
Measuring at between 5 and 7 on the Moh’s scale, turquoise is less durable than many gemstones used in jewelry, and this leaves it vulnerable to scratches and discoloration if exposed to cosmetics and perfumes. Sometimes stones are wax-treated to make them more resistant.
Turquoise is found mainly in Iran, Egypt and the United States, and to a lesser extent China, Australia, Afghanistan and India. It’s often found during large-scale copper mining operations in the US, but some experts believe it will become increasingly rare due to depleted mines.
Turquoise has had many names in the past, but its current name is derived from the French word turques (meaning Turks) - because it first brought to Europe from Turkey.
The stone is among the first ever to be mined. Its unique hue won it the affection of the rulers of Ancient Egypt, the Aztecs, Persians and the ancient Chinese. The Aztecs used it to decorate ceremonial masks.
Despite being well known in some areas of the world as a gemstone that protected the wearer’s well-being, it was not actually introduced to Europe until the 14th century and was completely unknown in Japan until the 18th century. It was popularized in part due to French excavations of Tutankhamun's tomb in the late 19th century, which revealed its importance to the Ancient Egyptians.
The value of turquoise depends on a stone’s TQI (Turquoise Quality Index) score. Stones are scored from zero to 100, and the price per carat can range from $0.01 to $1,000 depending on where it lies on that scale.
Generally speaking, turquoise is most valuable in radiant sky-blue shades and less valuable in green. And like many other opaque gemstones, turquoise has been devalued in recent years by the introduction of treatments, imitations, and synthetics into the market.
As mentioned above, turquoise is sometimes treated with wax in order to make it more durable. Pressure treatment using plastic or water glass is also used to improve durability.
Waxing, oiling and dyeing treatments are also used on turquoise to enhance its color and lustre.
Turquoise’s mystique goes beyond its radiant color - it’s also one of the most ancient gemstones and has played a key cultural role for thousands of years.
Although less durable than many other popular gemstones, turquoise is extremely versatile and is a fashionable choice in bracelets, necklaces, rings and earrings.