Alexandrite consistently emerges as the rarest birthstone, frequently cited for its unique optical properties and limited availability. However, black opal also holds a prominent position in discussions of gemstone rarity. This article will explore the characteristics, history, and significance of these two exceptional gemstones, drawing exclusively from available sources.
History and Lore
Alexandrite’s story begins in the Ural Mountains of Russia in the 1830s. Its discovery coincided with the coming-of-age of Prince Alexander II, to whom the gemstone was named. This association immediately imbued the stone with a sense of royalty and good fortune. Since its initial discovery, Alexandrite has been found in limited quantities in Sri Lanka, Brazil, and Zimbabwe, but the original Russian source remains historically significant.
Black opal, unlike its more common counterparts, displays a dark body tone that dramatically intensifies the play of iridescent colors within the stone. Primarily sourced from Australia, black opals have captivated gem enthusiasts for their striking appearance. While the history of opal itself stretches back millennia, the appreciation for the unique qualities of black opal is a more recent development.
Geological Formation and Sources
Alexandrite is a variety of the mineral chrysoberyl. Its formation requires a unique combination of minerals, contributing to its scarcity. The gem’s color-changing ability is a result of its complex interaction with light. The sources indicate that while initially discovered in Russia, Alexandrite is now found in Sri Lanka, Brazil, and Zimbabwe, though in limited quantities.
Black opal’s formation is equally specific. It is found predominantly in Australia, where unique geological conditions allow for the development of its dark body tone and vibrant play of color. The sources emphasize that unlike common opal, black opal’s dark background enhances the brilliance of the internal fire.
Gemological Properties
Alexandrite is prized for its dramatic color change. In daylight, it appears green, while under incandescent light, it shifts to shades of red, pink, or even brown. This phenomenon, known as the ‘alexandrite effect,’ is a key characteristic and a major contributor to its value. Alexandrite boasts a hardness of 8.5 on the Mohs scale, making it a durable gemstone suitable for various jewelry applications. It is a variety of chrysoberyl, further defining its mineralogical composition.
Black opal, a hydrated amorphous form of silica, also exhibits a captivating play of color. The dark body tone of black opal serves as a backdrop, intensifying the iridescent flashes of color within the stone. While not possessing the same color-changing ability as Alexandrite, its unique appearance and rarity make it highly desirable.
The following table summarizes key gemological properties:
| Property | Alexandrite | Black Opal |
|---|---|---|
| Mineral | Chrysoberyl | Hydrated Silica |
| Hardness (Mohs) | 8.5 | 5.5 - 6.5 |
| Color Change | Yes (Green to Red) | No |
| Key Feature | Color Change | Dark Body Tone |
| Primary Sources | Russia, Sri Lanka, Brazil, Zimbabwe | Australia |
Symbolism and Metaphysical Beliefs
While the sources do not extensively detail the symbolism associated with Alexandrite and black opal, diamonds, as a birthstone, are associated with love, purity, creativity, and power. The sources do not provide specific metaphysical beliefs tied to either Alexandrite or black opal. However, the rarity and beauty of these gemstones naturally lend themselves to associations with luxury, uniqueness, and individuality.
Care and Cleaning
Due to its hardness of 8.5 on the Mohs scale, Alexandrite is a relatively durable gemstone. Routine cleaning can be performed with warm, soapy water and a soft brush. Black opal, with a lower hardness of 5.5-6.5, requires more delicate care. Avoid harsh chemicals, ultrasonic cleaners, and prolonged exposure to water, as these can damage the stone. Gentle cleaning with a soft cloth is recommended.
Rarity and Value
Alexandrite is consistently identified as the rarest birthstone. Its unique color-changing properties and limited sources contribute to its high value. Red diamonds, while not a traditional birthstone, are also exceptionally rare and valuable. High-quality emeralds and rubies can also command significant prices, but Alexandrite and red diamonds often top the list due to their extreme scarcity. Tanzanite is noted as being 1000 times rarer than diamonds.
The sources indicate that diamonds are the rarest birthstone in six states, while white topaz is the rarest in Montana, Wyoming, and Rhode Island. This highlights the regional variations in gemstone availability and the complexities of defining “rarest.”
Regional Rarity of Birthstones
The sources indicate that the rarity of birthstones can vary by state. The following is a summary of the rarest birthstones by state, as indicated in the provided materials:
- Diamond: Rarest in six states (unspecified).
- White Topaz: Rarest in Montana, Wyoming, and Rhode Island.
- May, September, and June Birthstones: Scarce in Texas, Washington, and Utah, respectively (specific gemstones not identified).
Conclusion
Alexandrite and black opal stand out as exceptionally rare gemstones, each possessing unique qualities that contribute to their desirability. Alexandrite’s remarkable color-changing ability and limited sources, coupled with black opal’s striking dark body tone and vibrant play of color, make them highly sought-after additions to any gemstone collection. While diamonds are often considered the most expensive, the extreme scarcity of Alexandrite and red diamonds places them in a league of their own. The rarity of these gemstones underscores their enduring appeal and their significance in the world of gemology.