Black spinel, a gemstone characterized by its striking dark hue and impressive durability, has recently gained prominence as a modern birthstone for August. While peridot and sardonyx have traditionally represented this summer month, spinel—and specifically, black spinel—offers a bold and sophisticated alternative. This article will explore the history, geological origins, gemological properties, and symbolism of this captivating gemstone, drawing exclusively from available sources.
History and Lore
For centuries, spinel was often misidentified as other gemstones, most notably ruby. Historical accounts reveal that many famous “rubies” adorning royal jewels were, in fact, spinel. A particularly notable example is the approximately 170-carat Black Prince’s “ruby,” a red spinel that has been part of the British Imperial State Crown since 1367. It wasn’t until the 18th century that spinel was definitively distinguished from ruby based on chemical differences.
The name “spinel” itself originates from the Latin word spina, meaning thorn, a reference to the sharp, pointed crystals in which the gem often forms. While historically valued, spinel’s true identity remained obscured for a considerable period. The American National Retail Jewelers Association (JA) officially recognized spinel as an August birthstone in 1912, and more recently, it has been elevated to a primary birthstone for the month, joining peridot and sardonyx. This makes August one of only a few months with three designated birthstones.
Geological Formation and Sources
Black spinel is a naturally occurring gemstone formed through the activity of molten rocks. Its distinctive black color arises from the presence of magnesium aluminium oxide within its chemical composition. The gem crystallizes in a cubic system, known for producing sharp crystals.
Currently, major sources of spinel include Tajikistan, Myanmar, Sri Lanka, Vietnam, Tanzania, and Pakistan. Specific locations are known for producing spinel with particularly desirable colors; for instance, Myanmar is renowned for its hot pink and red spinel varieties. Black spinel, while found in these locations, is considered one of the rarer forms of this gemstone.
Gemological Properties
Black spinel boasts a hardness of 8 out of 10 on Mohs scale, making it a remarkably durable gemstone suitable for everyday wear. This hardness means it is resistant to scratching, comparable to topaz, and only surpassed by diamond, corundum (ruby and sapphire), and chrysoberyl. Its durability, combined with its striking appearance, makes it a popular choice for jewelry.
The gem’s composition is magnesium aluminium oxide, contributing to its deep, dark color. Black spinel exhibits adularescence, a milky luster, and a cubic crystal structure. When subjected to ultraviolet light, black spinel fluoresces with a natural red reaction under both long and short wavelength UV light.
Black spinels are available in a wide range of sizes, with some crystals reaching up to 18 carats in weight. They are commonly cut into various shapes, including round, oval, pear, and cushion cuts, as well as fancy cuts like octagon, baguette, trillion, and marquise. The cut refers not only to the shape but also to the proportion, symmetry, and finish of the gemstone.
A table summarizing key gemological properties is provided below:
| Property | Value |
|---|---|
| Hardness (Mohs) | 8 |
| Composition | Magnesium Aluminium Oxide |
| Crystal System | Cubic |
| Luster | Adularescence |
| Fluorescence | Red (UV light) |
| Common Cuts | Round, Oval, Pear, Cushion, Fancy Cuts |
Symbolism and Metaphysical Beliefs
While specific historical symbolism directly associated with black spinel is less documented than that of red spinel, red spinel, and other colored varieties, red gems were historically believed to be a remedy for blood loss and inflammatory diseases. They were also thought to ease anger and promote harmony. As a general birthstone for August, spinel is often associated with revitalization, renewal, and the energy of the summer months. The modern association of black with fashion and boldness lends itself to a symbolism of strength, sophistication, and individuality.
Care and Cleaning
Due to its hardness of 8 on the Mohs scale, black spinel is relatively durable and can be worn regularly. However, like all gemstones, it benefits from proper care. It is advisable to avoid exposing black spinel to harsh chemicals or ultrasonic cleaners. Cleaning can be performed using warm, soapy water and a soft brush. It is also recommended to store spinel jewelry separately from other gemstones to prevent scratching.
Conclusion
Black spinel represents a compelling addition to the family of August birthstones. Its striking appearance, impressive durability, and fascinating history make it a gemstone worthy of attention. From its past misidentification as ruby to its modern recognition as a primary birthstone, spinel’s journey reflects a growing appreciation for its unique qualities. Whether chosen for its aesthetic appeal, its symbolic meaning, or simply as a beautiful representation of the August summer season, black spinel offers a captivating choice for jewelry enthusiasts and gemstone collectors alike.