Different Turquoise treatment
by Ashutosh Roy
The main purpose of any treatment is to increase the hardness and reduce the porosity, in one word to increase the stability or the durability. The colour treatments help to enhance the glittering effect and to protect the stone from changing its colour, mostly called fading, due to sunlight, heat and common natural phenomena.
Treated Turquoise – ready to mount on your finger
As Turquoise is more of a legend than of a simple gemstone, we start here with a myth, which the Zuni used to believe. The Blue Turquoise is male, which comes from the sky and the Green Turquoise is female and comes from the earth. Whether it’s a male or a female, in reality both the male and female turquoises are too soft and sensitive to be mounted to your rings or bracelet directly from the mines.
Mostly the raw turquoises, which are extracted from the mines, are of very small sizes. In scientific jargon it is called cryptocrystalline, which means very tiny crystals to be viewed by a microscope only.
The softness is turquoise is too high; the hardness ranges between 2 to 6 if measured in Mohs scale. Again it is said, the better the quality of the turquoise, the softer the stone is. They are even softer than the glasses of windows. It is very difficult to cut the original turquoise due the porosity. These fragile turquoises are almost unusable for jewelry. Here you must notice that normally the turquoises are inlaid or carved in the jewelries with coral, jasper, pearls and sometimes with gold. And most of the associated jewels have got better hardness according to Mohs scale. This leads to the probability of cracks/ scratches etc. in the precious stone, turquoise. This is also to be noted that the specific gravity of the processed or treated turquoises becomes lower than the natural or virgin one.
So all turquoises, even including the high value turquoises also, are to be processed properly before mounting them in ornaments. Some common treatments are stabilization, waxing, coloring / dying. The main purpose of any treatment is to increase the hardness and reduce the porosity, in one word to increase the stability or the durability. The colour treatments help to enhance the glittering effect and to protect the stone from changing its colour, mostly called fading, due to sunlight, heat and common natural phenomena..
Most of the turquoises undergo a process called Stabilization. Some common treatments in the stabilization process include wax, staining, colloidal silica deposition, and plastics impregnation.
Light waxing and oiling as first treatment provides the wetting effect. This enhances the colour and luster of the material. In reality the wax treatment adds a layer of wax on the surface of the turquoise to prevent the turquoise from body oils and other chemicals and heat or sunlight from fading its colour. Waxing turquoise looks even finer. These are highly expensive and belong to gem grade.
To reduce the porosity, Turquoises are poured into epoxies or acrylic resigns or other substances, so that these are infused into the pores of the turquoise to form a solid turquoise. Once the poors are filled up, the hardness is automatically increased. Additionally the colour looks fresh. Just waxed or hardened by simple resign treatment does not decrease the value of the turquoise.
The Plastic impregnation is done by osmosis of hot plastics to the pores of the Turquoise to reduce porosity increasing the hardness and durability of the turquoise. Plastic impregnation or other simple hardness enhancer processes keep the value of the turquoise intact. It is also easy to identify the plastic stabilization, because a hot pin touching the Turquoise will result a deep mark in the stone and give off the smell of resign.
Sometimes pressure techniques are followed, when turquoises with epoxy or resign and plastic (such as polystyrene) are processed under high pressure by water glasses. This produces a wetting effect and improves durability.
There are several chemical treatments, which change or stabilize the colour of the turquoise to save you from fading your luck. Firstly turquoise is treated with chemical and then heated. This heating process filters the residual chemicals resulting a clean turquoise. This is called Zachary Process. The most significant part of this process is that the colour remains in tact over a longer-period of time without turning to a green colour. For buyers, according the ICA rules, the kind of coloring treatment must be indicated in the turquoise for sale.
Now, let us discuss a common question regarding the dark rings in the turquoise. Don’t forget that the mother stone of Turquoise is Matrix. So, if the stones were not cut with utmost care, then, matrix remains bound to the turquoise, producing dark rings in the turquoises. So, the dark rings are nor due to any treatment or chemical process, rather it is a impurity, comes with the turquoise.
Reconstituted turquoises mean chips mixed with resign before molded to proper shapes. Firstly pieces of turquoises are grinded to form Turquoise powder. Then the resign is mixed and finally heated. The molding turquoise is shaped according to the choice. This process results a natural hard and more stable materials. Turquoise formed by this artificial method is called reconstituted turquoise because they are basically manmade turquoises. As the proportion of resign is very high, a distinguish odor is smelt, reducing the value of the turquoise.
There are some very low categories of turquoises, which are called chalk or chip. The softness makes them unusable. They are of very low pricing and may be used for murals only, that too after several chemical and hardening processes.
The most desirable turquoises are the virgin turquoises, which have not undergone processing or treatment for enhancement of colour and hardness. They are simply shaped and polished after extracting from the mines. They are very costly as well as belong to the rare class.
Its very difficult to identify the proper turquoise and its value. Several methodologies have come up to detect the originality including Infrared testing equipments. So, either you need to consult a testing laboratory or depend upon the long-term relationship or the reputation of the jewellery shop. As the investment is very high and it may turn your luck also, a proper identification procedure is to be ensured.
Turquoise stands for strength and fortune. The belief is the enormous power may even stop flood. So you also need to work hard to achieve the stone to enhance your power or luck (!)