Because of turquoise’s soft and porous nature, ultrasonic cleaners and steam cleaners should never be used to clean turquoise jewellery. The gem should be cleaned with a soft, dampened cloth.Turquoise beads may darken over time if they are in direct contact with skin.
Natural, untreated turquoise with a bright luster and deep, blue homogenous colour – and no matrix veining is also highly collectible. The same holds true with turquoise that has known provenance.
“Spiderweb” matrix, containing fine dark lines with an attractive, even pattern surrounded by deep blue turquoise is preferred by some collectors. While turquoise from Persia (Iran) was a long a standard for the finest turquoise, material from the United States – specifically Arizona has proven to be of equal or greater quality in some cases.
Plastic impregnation: more durable gem
Wax impregnation: does not make the gem more durable. Treatment is sensitive to low heat
Dyeing: to deepen the color, simulate matrix
Filling – small cavities filled with a polymer to create a homogenous surface
Surface coating: lacquers, polymers used to coat the surface of the gem, deepening the colour
Reconstitution of turquoise dramatically changes the appearance of low quality turquoise fragments
The colour of highly desired turquoise is described as the blue of a robins egg, pale blue to blue-green to dark blue.
Deposits in China are known to produce a light to dark green turquoise with little or no blue component.
Turquoise is generally opaque
Turquoise can be fashioned into any shape, including carvings, though in most cases the material is cut in cabochon form. They are often fashioned as free-form beads (mostly with matrix) or perfectly homogenous, round beads with little or no matrix