Turquoise is one of the precious stones all over the world which has numerous mines in Iran. In fact, it must be said that Neyshabur turquoise is regarded as one of the most famous turquoises in the world dating back to seven thousand years ago.
Turquoise is a type of igneous rock that is found in volcanic areas and often near the surface of the earth. The degree of hardness of this stone is between 5.5 and 6 on the Mohs scale. It means that it has an acceptable hardness. Turquoise is generally composed of aluminum, copper, manganese, iron oxide and water. The best forms of turquoise are generally found in areas with hot and dry weather.
Turquoise is found in different colors: some are greenish and some blueish. The reason for this difference is the difference in the ratio of iron to copper. In general, the blue color of turquoise is due to the presence of copper element in it. The higher the amount of copper in turquoise, the bluer the color of turquoise.
Turquoise, with its attractive color varying between blue and green, is found in two general types of Persian and patterned. For example, in Iran, Persian variety is highly popular and it is sold at very high prices. However, turquoise stones are classified based on three different criteria including color, design, and mining location.
Persian Turquoise is the most precious turquoise and is found in blue and it is cut in a round or almond shape. This stone has no streaks and is completely smooth. It is good to know that Persian Turquoise is only found in Iran and it is very popular among Arabs.
Patterned Turquoise has prominent black or brown streaks. These streaks may be formed in regular or irregular patterns. If the patterns are irregular, it is called Patterned. This type of turquoise is cut into round, oval, teardrop and square shapes.
The more regular the patterns in turquoise and more similar to foliage, the more expensive it will be. The Patterned Turquoises with black streaks are known as spiderweb turquoise. In rare cases, the streaks may be gold which increases the price of the stone. In general, pale teal and teal colors are less valuable than the rest of the models.
There is also a type of turquoise similar to the patterned type called Arabic Turquoise. This stone has very thin and is considered of poor quality and is available in pale green color.
Different types of turquoise gems are made and sold by humans. Therefore, it is important to know how to identify the genuine turquoise. The first and easiest way to identify the original turquoise is to buy it from reputable stores and centers. But in general, based on the color and degree of hardness of the stone, you can recognize whether it is genuine or fake.
The color of genuine turquoise stones is usually slightly opaque. The original stone becomes pale and may turn white when placed under strong light, high heat, or in contact with fat. The original turquoise stone must not have black and white spots.
Another way to identify genuine turquoise is to pay attention to its back, i.e. its matrix stone (stone attached to the back of turquoise stone). For example, turquoises from Neishabur are seen as dark.
You can also drag a needle on the turquoise stone to determine its authenticity. If it leaves a scratch on the turquoise, it is probably a fake stone. If there is no scratch, the turquoise is genuine.
Since in some cases, polymers and plastics are used to make artificial turquoise, to detect such turquoise, you can heat a needle and drag it on the surface of the stone. If the needle leaves a trace on the stone and melts it, be sure that the turquoise is fake and made of plastic.
Turquoise mines can be found in Neishabur, Neygenan village in Mashhad, Baghou village in south of Damghan (Characteristic: gold streaks), as well as Shahrebabak in Kerman.
Heat can discolor the stone and damage its surface. Moreover, chemicals, cosmetics and even skin fat or human body sweat can cause the loss of turquoise color.