Many cutters try to produce stones that exclude the matrix, but sometimes it is so uniformly or finely distributed through the stone that it cannot be avoided
Copper is the primary element responsible for the blue and green colors in turquoise. The presence of varying amounts of Copper within the Stone can result in different shades of blue and green. Higher copper content tends to produce more intense blue tones, while increased iron content can shift the color towards green. Besides copper, iron and Zinc impurities can influence the color of turquoise. Iron can give Turquoise a greenish hue, while zinc can lighten the color and contribute to a bluish shade.
Blue Minerals are rare, and that is why turquoise captures attention in the Gemstone market. The most desirable color of turquoise is a sky blue or robin's-egg blue. Some people inappropriately describe the color as "Persian blue" after the famous high-quality material mined in the area that is now known as Iraq. Using a geographic name with a gem material should only be done when the material was mined in that locality. The crystals are microscopically small and can hardly ever be recognised with the naked eye.
The geographical location where turquoise forms can also contribute to color variations. Different regions have varying geological conditions, mineral compositions, and the presence of other elements. These factors can influence the color and appearance of turquoise Stones found in different locations. After blue, bluish green stones are preferred, with green and yellowish green material being less desirable. Departure from a nice blue color is caused by small amounts of iron substituting for Aluminum in the turquoise structure. The iron imparts a green tint to the turquoise in proportion to its abundance. The color of turquoise might also be altered by small amounts of iron or zinc substituting for copper in the turquoise structure.
Some turquoise contains inclusions of its host Rock (known as matrix) that appear as black or brown spider-webbing or patches within the material. Many cutters try to produce stones that exclude the matrix, but sometimes it is so uniformly or finely distributed through the stone that it cannot be avoided. Some people who purchase turquoise Jewelry enjoy seeing the matrix within the stone, but as a general rule, turquoise with heavy matrix is less desirable.
Some turquoise localities produce material with a characteristic color and appearance. For example, the Sleeping Beauty Mine is known for its light blue turquoise without matrix. Much of the turquoise from the Kingman Mine is bright blue with a spider web of black matrix. The Morenci Mine produces a lot of dark blue turquoise with pyrite in the matrix. Much of the Bisbee turquoise has a bright blue color with a chocolate brown matrix. People who know turquoise can often, but not always, correctly associate a stone with a specific mine.
Turquoise often forms in association with other minerals and host rocks. The presence of these materials can create matrix patterns within the turquoise stone. The matrix is the visible pattern or web-like design that appears as veins or patches within the stone. The matrix can range in color from brown to black and can have a significant impact on the overall appearance of turquoise. The water content within turquoise can affect its color. The amount of water present in the mineral structure can influence the intensity and saturation of the blue and green colors. Higher water content typically leads to more vibrant hues.
