Green turquoise is a beautiful semi-precious gemstone that has been prized for millennia for its striking color. The term “turquoise” actually refers to any mineral that is a hydrous phosphate of copper and aluminum, but the most desirable and valuable variety is the sky blue to green turquoise. The unique color of green turquoise comes from traces of iron and chromium in the gemstone’s composition. Understanding the factors that contribute to the range of green hues seen in turquoise can help appreciate the nuances of this fascinating gem.
What Causes the Green Color in Turquoise
Turquoise gets its characteristic blue-green colors primarily from copper, but variations in color come from small amounts of other elements. Here are the main factors that lend green shades to turquoise:
– Iron – When present in small amounts, iron gives turquoise a greener hue. Turquoise with higher iron content appears more green or yellow-green.
– Chromium – This element also causes turquoise to appear greener when present. The most valued turquoise has a pure sky blue color with little green, meaning low levels of iron and chromium.
– Dehydration – When turquoise loses some of its water content through natural processes over time, the color can shift toward greenish shades.
– Matrix – The matrix refers to the host rock in which turquoise forms. If the matrix has a lot of iron-bearing minerals, it can cause turquoise to be greener.
So in summary, iron, chromium, water loss, and a matrix rich in iron all contribute to turquoise appearing more greenish blue rather than pure blue. The most coveted turquoise with a intense sky blue color has very little of these color-altering elements and matrix effects.
Range of Green Colors in Turquoise
While pure blue is the most prized, turquoise actually occurs in a wide spectrum of blue and green shades. Here are some of the common color varieties seen in green turquoise:
– Seafoam green – Pale blue-green, reminiscent of the colors of the ocean. Seafoam turquoise has noticeable green tones from iron or chromium.
– Lime green – Vibrant yellow-green turquoise, caused by higher iron content.
– Forest green – Darker green gems with strong yellow-green or olive undertones, from significant iron.
– Teal – Bluish-green turquoise, considered more desirable than yellow-greens. The green tint likely comes from lower iron or chromium.
– Aqua – A pale, cool greenish-blue is characteristic of aqua turquoise, with subtle hints of green.
– Mint green – When turquoise has a distinctly greenish hue leaning toward light greenish-blue, it is termed mint green.
| Color | Description |
|---|---|
| Seafoam green | Pale blue-green |
| Lime green | Vibrant yellow-green |
| Forest green | Dark yellow-green |
| Teal | Bluish-green |
| Aqua | Pale greenish-blue |
| Mint green | Light greenish-blue |
This table summarizes some common green varieties of turquoise and their typical color characteristics. The wide range demonstrates the many subtle gradations between blue and green turquoise.
Most Valuable Green Turquoise Colors
When it comes to turquoise gemstones, the most coveted and valuable colors are the pure sky blues. Any noticeable green tint decreases value and desirability among jewelers and collectors. However, some shades of green turquoise are considered more appealing than others:
– Seafoam and teal turquoise – The paler blue-greens are preferred over the darker or yellow-leaning greens. The subtle green tint gives seafoam and teal gems an aquatic look that is still highly attractive.
– Aqua – The delicate greenish-blue aqua is also a favored hue, looking crisp and cool rather than muddy or dark.
– Mint green – For turquoise with clearly noticeable green, the pastel mint green is regarded as a pleasing color.
While not as lucrative as pure blue, turquoise in these shades of light blue-green can still command high prices, particularly for stones of large size and high quality.
Geographic Origins of Green Turquoise
The amount of green color in turquoise is heavily influenced by where the stone formed. Here are some of the leading sources of green turquoise worldwide:
– United States – American turquoise from Arizona, Nevada, New Mexico and California often has paler green shades from the chemical composition of the local rock. Kingman, Bisbee and Morenci turquoise are well known for seafoam hues.
– Iran – The arid climate of Iran yields turquoise with a sky blue color, so greener Iranian stones are less common. But Kerman province produces turquoise with more green from higher iron.
– Australia – Turquoise from localities like Broken Hill and Bourke have an unusually strong green tint from high iron in the environment.
– China – Chinese turquoise also tends to be quite green in color, ranging from aqua to deeper forest greens.
So while most turquoise has some variance of green, some of the most vivid and valued green turquoise comes from the southwestern United States. The chemistry of the host rocks here lends itself to greener shades.
Enhancement of Color in Turquoise
Since pure blue turquoise is so coveted, some turquoise is altered to improve the color. Here are some treatments used:
– Dyeing – Oil and wax dyeing can be used to change turquoise to a more desirable blue-green color. But dyed stones are considered less valuable.
– Impregnation – Impregnating turquoise with plastic, wax or oil fills in pores and results in richer sky blue color. This is considered an acceptable enhancement.
– Reconstitution – Finely ground turquoise is combined with resin to make solid gems of uniform color. But reconstituted turquoise has much lower value.
Naturally colored seafoam to teal turquoise maintains the highest value. Heavily treated stones are worth substantially less, so it’s important to buy from reputable sellers.
Caring for Green Turquoise Jewelry
Green turquoise, like all natural turquoise, requires some care to maintain its color and luster over time:
– Avoid chemicals – Turquoise can be damaged by acids, solvents and household cleaners. Avoid using chemicals when cleaning turquoise jewelry.
– Protect from sunlight – UV rays can cause turquoise to fade or change color. Keeping turquoise out of prolonged sun will help stabilize color.
– Take off when active – Turquoise is relatively soft, so take off rings, bracelets and other turquoise jewelry before physical activities to prevent abrasion or fractures.
– Store properly – Keep turquoise in a fabric-lined box or wrap in soft cloth to prevent surface scratches during storage.
With proper care, natural turquoise can retain its alluring greenish color for many years to come. But enhancement treatments may fade over time with exposure to sun and chemicals.
Conclusion
The range of green colors seen in turquoise gems comes from trace elements like iron and chromium interacting with copper in the mineral. Shades like seafoam, teal and aqua are among the most prized green turquoise hues. Natural color is always most valuable, so care should be taken to avoid treated stones. With appreciation for its nuanced green-blue shades, green turquoise stands out as a truly fascinating and beautiful gem.
