Demantoid

Demantoid is a rare and highly prized gemstone, a green variety of the mineral andradite, which is itself a member of the garnet group. It is known for its exceptional brilliance and fire, often exceeding that of diamonds, hence its name which derives from the German word "Demant" meaning diamond.

Properties and Characteristics

• Color: Demantoid is typically green, ranging from yellowish-green to intense emerald green. The most desirable color is a vibrant, saturated green.

• Dispersion: It possesses exceptionally high dispersion (0.057), which is the ability to separate white light into its spectral colors, resulting in a pronounced "fire" or colorful sparkle.

• Refractive Index: Demantoid has a high refractive index (1.880 – 1.889), contributing to its brilliance.

• Hardness: It has a Mohs hardness of 6.5 to 7, making it moderately durable but requiring care to avoid scratching.

• Inclusions: A characteristic inclusion found in some demantoid garnets is the "horsetail" inclusion, consisting of radiating fibers of chrysotile asbestos. These inclusions, while technically imperfections, are considered desirable by some collectors as they are a positive indication of origin (primarily from Russia).

Occurrence and Mining

Demantoid was first discovered in the Ural Mountains of Russia in the mid-19th century and quickly became popular, particularly during the Art Nouveau period. While the Ural Mountains remain a source, demantoid has also been found in other locations, including Namibia, Italy, Iran, Pakistan, and Madagascar.

Uses

Demantoid is primarily used as a gemstone in jewelry. Due to its rarity and brilliance, it is often set in rings, pendants, earrings, and brooches. Fine demantoid specimens can command high prices, rivaling those of other rare gemstones.

Value Factors

The value of demantoid is determined by several factors:

• Color: Intense, saturated green hues are most valued.
• Size: Larger stones are rarer and therefore more valuable.
• Clarity: Stones with fewer inclusions are generally preferred, although horsetail inclusions can increase value for some collectors.
• Cut: A well-cut stone will maximize its brilliance and fire.
• Origin: Russian demantoid, especially those with prominent horsetail inclusions, often commands a premium.

Care and Maintenance

Demantoid should be handled with care to avoid scratching. Clean it with warm, soapy water and a soft brush. Avoid exposing it to harsh chemicals or ultrasonic cleaners.