Turquoise Key Facts
- 2-6 on the Mohs scale of hardness
- Generally a blue stone, but could be green
- Turquoise is mainly found in Australia, China, Chile, Iran, Mexico, Tibet, Arizona and California
- Great care would be needed if this was used in an engagement ring as it is very soft
- December's birthstone
- The hour stone for 5am
- Turquoise is believed to help with new projects
General Information on Turquoise
Turquoise is a hydrated phosphate of copper and aluminium and is the birthstone for December. It usually occurs in dry regions, where rocks have been altered through the intrusion of other rocks from some volcanic or other thermal influence. Ground water slowly passes through aluminous rock surrounded by copper deposits. The copper is usually introduced into the rocks by rising hot magma. The copper oxidizes near the surface when it is in the magma and reacts with aluminium and phosphoric acid to form turquoise. Other minerals enter to make colour changes.
Turquoise is commonly found as an opaque deposit in nodules/veins within host rocks or as shallow crusts on the surface of rocks. Most turquoise contains patches or veins of the host rock in which it is formed. This is called Matrix. These include chalcedony, opal, brown limonite, black chert or white kaolinite, and can affect the colour and toughness of the stone.
In the past, the finest turquoise came from mines in Persia (Iran). Its French name means 'Turkish stone' which refers to the long history of imports of Persian material through Turkey to the west.
Turquoise is mainly found in Australia, China, Chile, Iran, Mexico, Tibet, Arizona and California and is often mined as a secondary mineral to copper. Mexican Turquoise is brighter in colour and has a purer colour with no matrix. Chinese turquoise is said to have softer matrix and is more porous than that from South America.
Turquoise is thought to date back as far as 5500BC. Like jade, turquoise was once thought to be more highly valued than gold.
Turquoise has a hardness rating of around 5 but can vary from 2 to 6 on the Mohs scale. Turquoise can be very soft and would need to avoid scratches and sharp blows and is therefore really not recommended for engagement rings. It is also sensitive to heat and chemicals and should not be ultrasonic or steam cleaned. For these reasons it would not be ideal worn in an every day ring, especially an engagement ring
Turquoise is Triclinic (has 3 unequal axes, none of which is perpendicular to another).
Its colour ranges from sky blue (caused by copper) to green (caused by iron or chromium) to yellowish green.
The majority of turquoise today is enhanced in one way or another. Turquoise, even top grade, is often coated with wax or oil to enhance its colour. It can also be fracture sealed, which means to seal with an acrylic resin to enhance its colour, texture and hardness. A pressure infusion of wax or epoxy resin is called stabilization. An electro-chemical enhancement called the Zachary process is an alternative to stabilization and can increase both durability and evenness of colour. Reconstructed turquoise is made from pulverised turquoise. Beads can be a composite material which is a treatment that involves a combining the ground or sections of gemstone which are then bonded with resin to create a smooth and even colour or for an interesting pattern or sometimes to improve durability.
Turquoise found in transparent to translucent visible crystals is rare and can be highly priced. The most admired stones are those of a robin's egg blue or celestial blue colour with no visible matrix. However, turquoise with a visible matrix can also be regarded as highly valuable if it has an even interconnected pattern of black matrix veins, which is known as spider web turquoise. Evenness of colour is an important consideration. Higher grades of turquoise are used for cabochons and carvings. The lesser grades are used more as polished beads or nugget style beads. Turquoise is rarely facetted.
There are numerous imitation turquoise made from plastic, ceramic and glass.
Turquoise is believed to help someone start new projects. It is also believed to warn the wearer of danger or illness by changing colour. Turquoise was once thought to protect the wearer from falling, especially from horses. Turquoise is more recently thought to be a good luck stone for aviators and flight staff and it is thought to bring happiness and good fortune.
It was believed that wearing turquoise on the little finger and looking at the stone after seeing the new moon would bring great wealth and turquoise is also a token of friendship
Not an ideal choice for your engagement ring but possible so long as the ring is not to be subject to any wear and tear.
Please contact us if you have any questions or would like to arrange a design consultation.