Turquoise is a striking blue-green colour that has been prized for millennia. The name originates from the French for Turkish, as the gemstone was first brought to Europe from Turkey. Turquoise jewelery and ornaments have been found dating back to ancient Egypt, and the vibrant colour has long been associated with beauty, serenity, and protection. In this article, we’ll explore the unique properties of the colour turquoise and examine why it has such enduring popularity.
The Origins of Turquoise
Turquoise is one of the oldest known gemstones and has been mined for over 6000 years. It is formed by the permeation of groundwater through aluminium and copper-rich rocks. The iconic blue-green colour is caused by traces of copper, while the aluminium provides the blue shades. The largest turquoise deposits are found in the arid regions of the American Southwest, Iran, Egypt and the Sinai Peninsula. Ancient peoples from these areas made extensive use of turquoise for jewellery and ceremonial objects. The Egyptians adorned the royal burial masks, including that of King Tutankhamun, with turquoise gems. Native American tribes believed the striking blue stones could bring good fortune and offer protection. The blue-green turquoise closely resembled the colour of the sky, and it was thought wearing the gem would ensure abundant crops and rainfall. This association with life and fertility is why turquoise has been considered a luck-bringing stone across many cultures.
The Properties of Turquoise
So what causes turquoise to display its distinctive colouring? Turquoise is a hydrous phosphate mineral containing copper and aluminium. It has the chemical formula: CuAl6(PO4)4(OH)8·4H2O. The copper gives turquoise its blue to green shades, depending on the concentration levels. Associated minerals in the stone such as iron can also influence the colour. Higher iron content will make the turquoise appear more blue. The aluminium provides some blue hues but is also responsible for turquoise’s characteristic lightness and porous nature. This creates the subtle variations in tone and unique veining that turquoise is prized for. The water content (hydration) in the mineral also contributes to its softness. This made it relatively easy for ancient artisans to carve into jewellery and ornaments.
Physical Properties
Here are some of the key physical properties of turquoise:
- Colour range – Sky blue to blue-green
- Hardness – 5-6 on the Mohs hardness scale
- Specific gravity – 2.60-2.90
- Refractive index – 1.61-1.65
- Lustre – Waxy to subvitreous
- Transparency – Opaque
- Streak – Bluish white
The low hardness makes turquoise susceptible to scratching and weathering. But it also meant ancient artisans could shape it with simple hand tools. The waxy lustre and opaque transparency give turquoise a distinctive glowing sheen.
Turquoise Colour Variations
While blue-green is considered the classic turquoise tone, it can vary from sky blue to greener teal shades. Here are some of the factors that influence turquoise’s colouring:
Copper Content
Higher concentrations of copper in the mineral structure produce richer, more blueish greens. Less copper results in paler, greener shades. Iranian turquoise often has higher copper levels and displays deeper blue-greens.
Matrix
Turquoise usually contains veins of darker material called the matrix. This is made up of the mother rock and other minerals like pyrite. More matrix results in a greener tone. Unmatrixed turquoise with little veining is rarer and bluer in colour.
Water Content
Higher water content in the mineral structure will increase the blue shades. Lower hydration produces a greener look.
Associated Minerals
Iron, zinc and chromium in the turquoise can modify the blue-greens. Iron tends toward blue while zinc and chromium make it greener.
Weathering
Exposure to light and moisture can cause the copper in turquoise to oxidize, fading it to paler shades of green over time. Well-preserved turquoise retains its blue tones.
Turquoise Colour Grading
The most valued and intense turquoise tones range from sky blue to a vivid robin’s egg blue-green. The basic colour grading for turquoise from most to least valuable is:
Persian
Rich sky blue, intensely and evenly coloured. No veining or matrix. Found mainly in Iran.
Sky Blue
Light azure blue with some thin darker veining. Uniform colour.
Robin’s Egg Blue
Brilliant blue-green with no matrix. Named for its resemblance to robin’s eggs.
Medium Turquoise
Classic blue-green tone. Some dark veining evident. Most familiar turquoise colour.
High Blue
Intense blue-green but with noticeable veining and matrix.
Light Turquoise
Pale greenish-blue with heavy dark matrix.
Lime Turquoise
Yellowish green with little blue. Heavily webbed matrix.
So turquoise spanning the sky blue to blue-green spectrum is the most valuable. Pale greens and heavily matrixed stones are less prized.
Famous Turquoises
Some of the most famous turquoises displaying a coveted deep blue colour are:
Sleeping Beauty
Vivid sky blue found in Arizona. Highly prized and expensive.
Bisbee
Deep robin’s egg blue from Arizona copper mines. No matrix.
Persian
Intense blue stones from Iran, considered the world’s best.
Skyscraper
Azure blue turquoise from a Nevada mine. High copper content.
Kingman
Blue-green turquoise from Arizona. Has some thin black veining.
The most valuable turquoises globally come from Iran and the Southwestern United States. Iranian stones set the standard for pure sky blue colouring.
Turquoise Meaning and Symbolism
What has made turquoise endure as a popular gemstone across numerous cultures for thousands of years? Here are some of the symbolic meanings attached to its distinctive colour:
Protection and Healing
Turquoise’s blue-green shade is thought to have protective powers and promote inner tranquility and healing. It is said to keep the wearer safe from harm.
Power and Wisdom
Shamans and medicine men adorned themselves in turquoise as a sign of power and wisdom. The colour blue also represented the life-giving forces of water and the sky.
Fertility and Luck
Turquoise was seen as an assurance of bountiful rains, crops, and herds. The vibrant blue-green was thought to guarantee good fortune.
Courage and Friendship
In Persia, turquoise was the colour of courage and bonded friendships. Exchanging turquoise gifts cemented a loyal bond.
Eternity and Immortality
Ancient Aztecs and Mayans used turquoise to represent eternity. The enduring, changeless blue-green signified the heavens and immortality.
So turquoise has long been symbolic of life, power, protection, and the eternal forces of the sky and water. Even today, many still feel an innate attraction to the striking blue-green shades.
Uses of Turquoise
What are some of the ways this vividly coloured gemstone is used? Here are some of the main applications:
Jewellery
Turquoise has been fashioned into personal adornments and jewellery for thousands of years. It is used in necklaces, rings, bracelets, pendants, and other ornaments. The striking blue-green pairs well with silver and copper tones.
Decorative Objects
Sculptures, vases, bowls, figurines, tablets, boxes and tiles have been decorated with turquoise for its beautiful colour. Many Persian and Turkish mosques contain turquoise tilework.
Paints and Dyes
The pigment CuAl6(PO4)4(OH)8·4H2O has been made from high quality turquoise to produce vivid oil and watercolor paints. A blue-green dye can also be extracted from the gem.
Protective Amulets
Turquoise is carved into beads, animals, motifs and other shapes to make protective amulets.Horse riders in Asia wore turquoise amulets believing they shielded the animal.
Mosaics and Inlays
Crushed turquoise is used to create mosaics and inlaid ornamentation by compacting it with epoxy or resin. This adorns boxes, furniture, walls, fountains and more.
So turquoise has enjoyed wide decorative use and retains symbolic protective powers as amulets. Its popularity has endured across cultures for millennia.
Caring for Turquoise
While a durable gem, turquoise still requires some care, especially during cleaning and storage:
- Avoid ultrasonic or steam cleaners which can damage the stone.
- Use very mild soap and water to gently hand clean turquoise.
- Rinse thoroughly after cleaning and dry immediately with a soft cloth.
- Store turquoise separately from other gems to prevent scratching.
- Keep away from harsh chemicals like bleach, acid, and cosmetics.
- Avoid exposing turquoise to prolonged direct sunlight.
- Select gold, silver, or platinum settings instead of softer metals.
- Remove turquoise jewellery before heavy work or exercise.
- Consider a protective coating for carved turquoise objects.
Handle turquoise delicately and take measures to limit damage from knocks, chemicals, and scratches. With some basic care, this strikingly coloured gem will remain an eye-catching addition to your wardrobe or home.
Conclusion
The vibrant blue-green turquoise has fascinated humankind for millennia with its striking colour and symbolic meanings. This ancient gem continues to be coveted for jewellery, ornaments, decorative objects and amulets. Turquoise coloured by traces of copper ranges from sky blue to deep teal greens. Its distinctive tone is influenced by the associated minerals present and the amount of matrix veining. This beautiful hydrous phosphate mineral’s enduring allure and popularity prove that the colour turquoise will always be prized.
