(Karat gold, turquoise and diamond necklace, David Webb; image courtesy of Sotheby’s.)
A matrix, unlike the film trilogy, is a mass of fine-grained rock that plays host to gems, crystals and fossils as well. The matrix often leaves marks on its guests; the turquoise in question is marked by its host rock with a spider-web pattern of inclusions in shades of brown or black. Sometimes these patterns are so finely and evenly distributed that jewellers opt to leave the natural pattern in instead of cutting them out. However, it has to be noted, that stones without the matrix inclusions are preferred.
Cabochons, beads and others forms are possibilities for natural untreated turquoise gems where they can be turned into jewellery and are in high demand because untreated turquoise stones are rare. Treated turquoise stones are those infused with some sort of binding agent to make the stone a lot harder than what it is when it arrives straight from the mine and also where the colour is enhanced. Mined stones are often too porous to cut into and must be treated with polymers before they are ready to be cut; this reduces the value of the stone.
(Spider-web turquoise Navajo cuff; image courtesy of Pinterest.)
The intensity of the colour (a strong shade of blue, preferably sky-blue to the blue of a robin’s egg) and the hardness of the turquoise are what determine the stone’s value. Copper plays a significant role in the colouring of this stone. The gemstone is of a rather delicate nature wherein it can be tainted by perfume, cosmetics or solvents of any sort which is why certain care must be taken and too much direct exposure to sunlight should be avoided as much as possible.
Dyed stones and imitation pieces have ruined things for this gem market-wise which is why it is always best to be careful while making purchases. So be cautious and make sure your source is a reliable one.