Turquoise
| Property | Details |
|---|
| Mineral | Turquoise (copper aluminum phosphate) |
| Mohs Hardness | 5 – 6 |
| Refractive Index | 1.610 – 1.650 |
| Birthstone | December (alternative) |
| Major Sources | Iran (Persian), Arizona, Nevada, New Mexico, China |
| Treatments | Stabilization with wax or resin (very common) |
Overview
Turquoise is one of the oldest gemstones in human history, used in jewelry and adornment for over 5,000 years. Its distinctive opaque blue to blue-green color is instantly recognizable and deeply associated with the American Southwest, where it holds spiritual significance in Native American culture.
Varieties & Origins
Persian turquoise from Iran has historically been considered the finest, displaying an even robin's-egg blue without matrix. American turquoise from Arizona (Sleeping Beauty, Kingman, Bisbee), Nevada, and New Mexico is highly valued and comes in a wider range of blues and greens, often with attractive spider-web matrix patterns. Chinese turquoise is the largest commercial source today. The matrix pattern (brown or black veining from surrounding rock) is a matter of personal preference—some prefer clean blue, while others value intricate spider-web patterns.
Quality & Value Factors
The finest turquoise is an even, robin's-egg blue with no matrix. However, attractive spider-web matrix can actually increase the value of certain American turquoise varieties. Hardness varies widely; harder turquoise takes a better polish and is more durable. Most turquoise is stabilized with wax, resin, or polymer to improve durability and color, a common and accepted practice. Untreated, natural turquoise of fine quality commands a significant premium.
Care & Cleaning
Turquoise ranks 5 to 6 on the Mohs scale and is porous. Keep it away from oils, perfumes, chemicals, and prolonged sunlight. Clean with a damp cloth only. Never use ultrasonic cleaners, steam cleaners, or chemical solutions. Turquoise is best suited for earrings, pendants, brooches, and carefully worn rings.
Frequently Asked Questions
What is the difference between Persian and American turquoise?
Persian turquoise from Iran has historically been considered the finest quality, characterized by an even, robin's-egg blue color without any visible matrix (veining). American turquoise from Arizona, Nevada, and New Mexico comes in a wider range of colors from sky blue to green-blue and often features attractive spider-web matrix patterns. Both types are highly valued but for different reasons: Persian for its pure, even color, and American for its character and distinctive matrix patterns.
What is turquoise matrix?
Matrix refers to the brown, black, or gray veining patterns visible in many turquoise stones. These patterns come from the host rock (usually limonite or sandstone) in which the turquoise formed. Spider-web matrix, with thin, even lines creating a web-like pattern, is highly sought after in American turquoise. Some collectors specifically prefer matrix turquoise for its unique character, while others prefer clean, matrix-free material. The desirability of matrix is largely a matter of personal taste and cultural tradition.
Is turquoise stabilized or treated?
Most commercial turquoise has been stabilized with wax, resin, or polymer to improve its durability and deepen its color. Only about 10% of turquoise mined is hard and fine enough to be used in its natural state. Stabilization is widely accepted in the trade and creates a more durable stone that maintains its appearance over time. Untreated, natural turquoise of fine quality is significantly rarer and more expensive. Reconstituted turquoise (made from powdered turquoise bound with resin) is the lowest quality and should be disclosed.
Why does turquoise turn green?
Turquoise can turn green over time due to several factors: exposure to body oils, cosmetics, perfumes, and chemicals can alter the stone's chemistry. Light and heat can also affect the color. The copper in turquoise is responsible for its blue color, and when it reacts with acids, oils, or other substances, it can shift toward green. Stabilized turquoise is more resistant to color change than untreated material. To preserve color, keep turquoise away from chemicals and store it properly.
Is turquoise durable for jewelry?
Turquoise ranks 5 to 6 on the Mohs scale, making it one of the softer gemstones used in jewelry. It is porous and susceptible to damage from chemicals, oils, and impacts. Turquoise works best in earrings, pendants, brooches, and carefully worn rings with protective settings. For rings, bezel settings offer the best protection. Stabilized turquoise is more durable than natural material. With proper care and awareness, turquoise jewelry can last for generations.
Specialty & Collector Gemstones