Demantoid
Demantoid garnet is one of the most captivating green gemstones, highly prized for its brilliance and rarity. It belongs to the andradite variety of garnets, known for their stunning optical properties, including a high refractive index and vivid dispersion, often referred to as “fire.” The unique green hue of demantoid makes it one of the most desirable members of the garnet family, frequently sought after by collectors and jewelry enthusiasts alike.
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Demantoid Garnet: Composition and Characteristics
Andradite garnet, of which demantoid is a green variety, is a calcium and iron-rich mineral with the chemical formula Ca3Fe2(SiO4)3. The vibrant green coloration of demantoid is primarily due to trace amounts of chromium, while ferric iron contributes to a subtle yellow tint that can be present in some specimens. This unique combination of elements gives demantoid its characteristic color, ranging from bright yellowish-green to a rich, deep emerald-like green.
Misnomers in the Gemstone Market
In the gemstone market, demantoid garnet is sometimes mistakenly referred to as “olivine” or “Uralian emerald.” Despite these misnomers, it stands distinct due to its brilliant optical properties and specific chemical structure.
Heat Treatment in Demantoid Garnet
In approximately 2003, reports emerged indicating that some Russian demantoid garnets were subjected to heat treatment to enhance their green coloration. This treatment, performed at relatively low temperatures, aims to improve the stone’s visual appeal, making it more desirable for the jewelry market. Importantly, these heat treatments are thought to be undetectable through standard gemological testing, making it crucial for buyers to source their gems from reputable dealers who can provide reliable provenance information.
Shades of Green: The Beauty of Andradite Garnet
Demantoid garnet always exhibits a primarily green hue, but the exact shade can vary significantly. The color spectrum ranges from intense, vibrant yellowish-green to a deep, almost emerald-like green. Occasionally, a brownish tint may be present, caused by higher concentrations of iron. This color variability is one of the reasons collectors find demantoid so fascinating—each stone tells its own unique story through its color and internal features.
Optical Properties of Demantoid Garnet
One of the most notable optical properties of demantoid is its high dispersion of 0.057, which often results in “fire,” or rainbow-colored flashes of light that can be seen when the stone is exposed to direct light. However, in some instances, the deep green body color may slightly mask this dispersion. Demantoid garnets possess an adamantine luster, adding to their dazzling brilliance, and have a high refractive index ranging from 1.80 to 1.89, contributing to their striking visual appeal.
Size and Value of Demantoid Garnet
Demantoid garnets are typically found in smaller sizes compared to other gemstones. Most faceted stones weigh less than 1 carat (200 mg), while stones over 2 carats (400 mg) are considered rare, and those above 3 carats (600 mg) are extremely rare. The value of a demantoid garnet is largely influenced by its size, color saturation, and clarity. Stones with a more vivid and intense green coloration are generally the most highly prized. However, lighter green stones with a yellowish hue often exhibit more pronounced fire, making them equally attractive to some buyers who prefer this unique optical effect.
Horsetail Inclusions: A Hallmark of Russian Demantoid
One of the most distinctive features of Russian demantoid garnets is the presence of inclusions known as “horsetails.” These are fibrous inclusions of chrysotile, a type of asbestos, which radiate from a small central crystal of chromite. These feathery golden threads resemble the tail of a horse, hence the name “horsetail inclusions.” In gemology, the presence of horsetail inclusions is often regarded as diagnostic for natural demantoid, providing a clear indication of the gem’s authenticity and origin.
The Value of Horsetail Inclusions
Interestingly, horsetail inclusions can add significant value to a demantoid garnet. Unlike most other gemstones, where inclusions tend to lower value, the presence of horsetails in demantoid is seen as a desirable feature, particularly when they indicate Russian origin. Russian demantoids are considered the finest examples of this gem, and the presence of these characteristic inclusions can significantly enhance a stone’s value. That said, demantoid garnets from other locations, such as Italy and Iran, may also contain horsetail inclusions, but their appearance tends to be slightly different and may not always carry the same premium as Russian stones.
Geological Origins and Formation
Demantoid garnet was first discovered in the Ural Mountains of Russia in 1853, and for many years, this remained the only known source. The Ural deposits produced some of the most exceptional stones, known for their deep green color and prominent horsetail inclusions. In 1996, a significant new deposit was discovered in Namibia, known as the Green Dragon Mine, which brought additional supply to the market and added diversity to the available material. Subsequently, other deposits were discovered in Madagascar and Iran, each contributing their own unique qualities to the demantoid family.
Characteristics of Demantoid from Different Regions
Namibian demantoid is known for its bright green color and often excellent clarity, though it lacks the horsetail inclusions that are so highly prized in Russian material. Meanwhile, stones from Italy and Iran may exhibit similar characteristics to Russian stones, including horsetails, but with a distinct mineralogical profile suggesting a serpentinite geological origin. Understanding the different sources of demantoid garnet helps collectors and gem enthusiasts appreciate the nuanced characteristics that each region imparts to these stunning gemstones.
Sample from Namibia
Demantoid Garnet: Meaning and Healing Properties
The following section is pseudo-scientific and based on cultural beliefs.
In crystal healing, demantoid garnet is believed to possess numerous beneficial properties. Physically, it is said to help with improving eyesight, unblocking arteries, boosting the immune system, and supporting the respiratory system, especially in cases of bronchitis or pneumonia. Like other garnets, it is also believed to aid in enhancing bone marrow function, alleviating symptoms of arthritis and rheumatism, and improving the body’s ability to assimilate Vitamin A.
Emotional and Spiritual Benefits
Many people who practice crystal healing consider demantoid to be a powerful stone for enhancing vitality and energy. Its vibrant green color is associated with renewal and regeneration, making it a popular choice for those seeking to foster a sense of growth and well-being. However, it is important to note that these claims are not scientifically verified and should be regarded as a matter of personal belief rather than medical advice.
Frequently Asked Questions (FAQ)
Is demantoid garnet valuable?
Yes, even with the discovery of new sources since the 1990s, demantoid garnet remains one of the rarest and most valuable varieties of garnet. Clean, facetable stones command very high prices per carat, especially those with rich green colors and characteristic horsetail inclusions. The combination of rarity, optical brilliance, and historical association with Russian gemstones makes demantoid highly sought after in the gemstone market.
Where does demantoid garnet come from?
Demantoid garnet was first discovered in the Ural Mountains in Russia in 1853, and the Russian deposits remained the only source until a major discovery was made in Namibia (Green Dragon Mine) in 1996. Since then, additional deposits have been found in Madagascar, Italy, and Iran, each contributing its own unique characteristics to the range of demantoid gemstones available today.
What is the difference between demantoid and tsavorite garnet?
Demantoid and tsavorite are both green varieties of garnet, but they have distinct differences. Demantoid is a type of andradite garnet, known for its exceptionally high refractive index and dispersion, which can be higher than that of diamond. This property results in the characteristic “fire” that is often seen in demantoid. Tsavorite, on the other hand, is a type of grossular garnet, known for its vivid green color but typically lacks the same level of dispersion and fire as demantoid. Both garnets are prized for their beauty, but demantoid is generally rarer and more valuable.
Where is demantoid found?
Demantoid garnet has been found in several locations around the world, including Russia, Namibia, Madagascar, Italy, and Iran. The Russian material, particularly that from the Ural Mountains, continues to be the standard by which all other demantoid garnets are judged. These stones are often characterized by their deep green color and the presence of horsetail inclusions, which are less common in demantoid from other locations.