Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue.
In recent times, the value of turquoise, like most other opaque gems, has been affected by the introduction of treatments, imitations, and synthetics onto the market. As a gem collector, one has to be very careful in selecting and buying this gem to add to your collection. It is said that over 90% of turquoise in the market is not natural. The brightly coloured stones are either treated or man made to look like the real turquoise stones. These imitation stones are compressed powder and painted outside to deceive innocent buyers.
|The natural stone, or is it?|
|Imitation turquoise showing the interior|
|A genuine turquoise with the characteristic blue hue|
Turquoise is treated to enhance both its colour and durability (i.e., increased hardness and decreased porosity). As is so often the case with any precious stones, full disclosure about treatment is frequently not given. It is therefore left to gemologists to detect these treatments in suspect stones using a variety of testing methods.
Treatment methods include waxing and oiling, stabilization and dyeing. Recompression of small fragments of turquoise in powder form and bonded with resin to form a solid mass.
Originally, light waxing and oiling were applied to turquoise to provide a wetting effect, thereby enhancing the colour and lustre. This treatment is more or less acceptable by tradition, especially because treated turquoise is usually of a higher grade to begin with. Due to its porous nature, turquoise is often treated with plastic or water glass to stabilize its interior. This process consists of pressure impregnation of the porous material by epoxy and plastics (such as polystyrene) to produce a wetting effect and improve durability. This treatment is far more permanent and stable than waxing and oiling, and can be applied to material to provide sufficient improvement in hardness and stability. Conversely, stabilization and bonding are rejected by some as too radical an alteration as it damages the internal structure of the material.
The use of Prussian blue and other dyes (often in conjunction with bonding treatments) to "enhance" colour is regarded as fraudulent by some purists, especially since some dyes may fade or rub off on the wearer. Dyes have also been used to darken the veins of turquoise.
|Some turquoise has the porcelain type of finishes|
|A red agate stone separating the turquoise beads|
|A beautiful master piece of art|
|High quality turquoise carving|
|A turquoise necklace|
I like turquoise. But due to lack of understanding of this gem, the first few turquoise necklaces I bought were unfortunately fakes even tough they looked like the real thing. I have since returned them to the shop for some things else.
Finally I managed to get a genuine turquoise bracelet through a friend who trades in gems. It is bluish green in colour and the beads are not that even in size. I shall talk more about it next time.