It may lack the transparency and sparkle of the transparent gemstones, but Turquoise has nothing to envy from any other gem. Its rich colour, its lengthy history, its relation with the humans throughout the world and its gentle feel when touched or worn against the skin, make people desire it.
The name Turquoise, that translates as “Turkish stone”, derives from the fact that the gem was brought in Europe by Levantine traders, through Anatolia, reaching the Mediterranean region by passing across the areas of Turkey. The same name is used to describe its easily recognizable blue-green characteristic colour.
The oldest mention of turquoise comes from ancient Egypt where burial masks, funerary objects and other ornaments carved out of this gem that date back to 3000 BC have been found;for example, we encounter turquoise in the inlays of the important golden death mask of Tutankhamun. The great goddess Hathor of ancient Egypt was also called the “Mistress of Turquoise” and was the protector of the turquoise miners, the patron of the mines and consequently of the whole Sinai peninsula.In ancient Persia, turquoise was used as a protective talisman, a belief that has been transmitted throughout the years so that turquoise is still used today as protection against the evil eye in many markets of the world. The thirteen century Persian Scholar Al-Qazwini has written: “The hands that wear a turquoise and seals with it will never see poverty”. The name that the ancient Persians used for turquoise was “pirouzeh” that means victory.
Turquoise was also a particularly favoured material by Mixtec and Aztec civilizations and was often used by the artists as a mosaic material to cover statues and masks dedicated to the gods. A famous artifact, that dates back to the Aztec art, is a human skull that is decorated with turquoise chips, and believed to represent the god Tezcatlipoca, one of the creator gods and perhaps the most important deity in the Aztec pantheon.
Only by hearing the word turquoise a vivid sky blue color comes to mind, but the actual gemstone’s hues may vary from a blue to a green-blue down to a vivid yellowish green. Although the blue colour may be highly valued, the international market puts a great value to the other hues as well. In fact, finely textured and evenly colored green turquoise may fetch quite high prices. The difference in the possible hues depends on the presence, quantity and chemical state of chromophore chemical elements such as copper and iron. Also, because of the fact that the turquoise used for jewelry is a cryptocrystalline aggregate and not a single crystal gem, it tends to absorb contaminants from the environment which may cause its discoloration or staining. The iron that turquoise naturally contains may oxidize with time for various reasons, and result in the turquoise acquiring a greener hue. People often misunderstand this natural property of turquoise and misinterpret it as if there is “something wrong” with their gem.
The turquoise that is generally accepted as being of the highest quality is the finely textured one that exhibits an evenly distributed ,medium toned, intense blue colour, with no evident color mottling or matrix. This kind of turquoise is often sold as “Persian”, although it may not originate from Iran, because traditionally the highest qualities of turquoise were found in the Persian mines. Other market terms that are used to indicate different varieties –and not necessarily sources- include the “Mexican” or “American” which is used to describe the lighter toned material, while the term “Egyptian” is commonly used for the greenish hues.
Apart from the colour, turquoise is also classified based on its texture and the presence or absence and type of matrix. As mentioned before, being an aggregate means that the material is composed of many tightly grouped microscopic crystals. The smaller these crystals are and the more tightly they are bonded to each other, the finer the texture of the turquoise. This means that not only the material will be tougher and more resistant to blows, but it will take a higher polish and it will be less porous, so discoloration will be more difficult to happen. In fact, finely textured untreated turquoise has smooth surface and elegant waxy luster.
Sometimes, turquoise may be scattered through its host rock in a way that cutting away all the rock would result in very small specimens. In these cases, the cutters fashion the turquoise so that parts of the rock are included in the finished gem. Matrix, or else, these portions of the host rock present on the polished gem, can affect turquoise’svalue. The matrix we may find on natural turquoise can range from light brown to almost black, depending on the type of rock where the gem formed. Generally speaking, the market prefers turquoise without any matrix. However, if it is evenly distributed throughout the gem and there is a nice balance between the turquoise and the matrix, the material can still be desirable, as the delicate dark web-like patterns create an attractive contrast with the brightly colored gem.
Since turquoise tends to absorb foreign contaminants that would eventually alter its appearance by darkening or discoloring it, people in the market try to protect it by applying colorless substances on it –simply wax or oils, or more sophisticated polymers- , so that its surface is “sealed”. The same treatment would also add to the luster of the gem and make it somewhat more durable as the protective substance would fill the tiny spaces between the aggregate’s microscopic crystals. This polymer-impregnated turquoise is known as “stabilized turquoise” in the market.
Another misconception considering turquoise is a misleading term that is commonly used in the market, the so-called “reconstructed” turquoise. Most of the times, the material sold as reconstructed or reconstituted turquoise contains no turquoise at all; it is just a mixture of powdered materials with blue dye, bonded together with resin or plastic.
Although people may erroneously think that turquoise is a “semi-precious” material and that is does not have high value, the truth is very different. High quality natural turquoise is scarce and its supply is very limited, fact that leads to high value and thus high prices. The Nishapur district of Iran is still producing some of the world’s best turquoise. The southwest US, and particular the “Sleeping Beauty” Mine in Arizona is probably the top turquoise producer in terms of quantity, while top colour material comes mostly from the mines in Hubei Province of China.
Turquoise is a joyous gem that with its lively color makes us feel happy. In it, people have always seen the immensity of the bright skies combined with the colour of the sea as it sparkles with green and blue flashes under the sun. When Aquarius caused the great flood of the earth in order to punish the humankind for their misbehavior, Deucalion and his wife Pyrrha survived and were told they should repopulate the Earth. After asking for the oracle of Delphi about how to complete this task, they were told that the only way to do it was to walk on the land and throw the bones of their mother behind them. The way they interpreted this was that they should throw rocks along their path, as the rocks are the bones of mother Earth. Those stones were soaked in the flood and had turned into turquoise. As they tossed the turquoise stones over their shoulders, the new women and men of this Earth were created.
This article was first published in the Jewellery Historian Magazine – Issue 12
