The birthstone for August 24th, and indeed the entire month of August, is a subject of modern evolution within gemology. While peridot has long been recognized as the primary birthstone for August, the official modern list has expanded to include additional gems that offer greater choice and variety. Among these, spinel stands out as a particularly compelling and durable option. As a gemstone that occurs in a vibrant spectrum of colors, most notably in shades of red and blue that closely resemble the world's most prized gems, spinel offers both beauty and resilience. Its status as a birthstone is a relatively recent development, yet it is rooted in a history of mistaken identity and remarkable geological formation. This article will explore the multifaceted nature of spinel, delving into its history, geological origins, gemological properties, and its journey to becoming a celebrated modern birthstone for the month of August.
History and Lore: From Misidentified Royal Jewels to a Recognized Gem
For centuries, spinel was often mistaken for more famous gemstones, particularly ruby and sapphire. Many of the world's most famous "rubies," such as the Black Prince's Ruby and the Timur Ruby in the British Crown Jewels, have been identified as spinel. This historical confusion stems from the fact that red spinel can bear a striking resemblance to ruby, leading to its misidentification in royal collections and historical records. The gem's journey to recognition is a testament to the evolving science of gemology. It wasn't until the 18th century that spinel was formally distinguished from ruby, yet its association with these prestigious gems has lent it an air of historical significance.
The inclusion of spinel on the modern birthstone list is a more recent phenomenon. The first official modern birthstone chart in the United States was established by the National Association of Jewelers (now Jewelers of America) in 1912. This initial list did not include spinel. However, the list has undergone revisions over time to reflect changing tastes and market availability. A significant update occurred in 2016 when the American Gem Trade Association added spinel as an additional birthstone for August. This addition was driven by spinel's desirable qualities, including its wide range of colors and exceptional durability, which make it an excellent choice for jewelry intended for daily wear. Prior to this, the August birthstone list had already been expanded to include sardonyx, a banded variety of chalcedony, though its inclusion is noted as being on "some (but not all) birthstone lists." The evolution of the August birthstone list—from the traditional sardonyx to the modern peridot and now the inclusion of spinel—demonstrates how birthstone charts adapt over time, offering more options to those born in this month.
Geological Formation and Sources
Spinel is a magnesium aluminum oxide (MgAl₂O₄), a mineral that forms under specific high-temperature, low-pressure metamorphic conditions. It is commonly found in limestone and dolomite, where it crystallizes during the metamorphism of magnesium-rich rocks. The gemstone is also found in alluvial deposits, having been eroded from its original host rock and transported by water over time. These placer deposits are often a significant source for gem-quality spinel.
While spinel occurs in many locations around the world, certain regions are particularly renowned for producing high-quality specimens. Historically, the most famous source of red spinel was the Badakhshan region of Afghanistan and Tajikistan, which supplied the gems for the royal jewels of Europe and Asia. Today, significant sources include Myanmar (Burma), which is known for producing vibrant red and pink spinels, as well as Sri Lanka, which yields a variety of colors. Vietnam is also a notable source for spinel, particularly in blue and violet hues. Other sources include Thailand, Tanzania, and Madagascar. The geographic diversity of spinel deposits contributes to the gem's wide array of available colors, from the coveted "ruby-red" to deep blues, pinks, purples, and even colorless varieties.
Gemological Properties
Spinel is prized not only for its color but also for its excellent physical properties, which make it a durable and practical gemstone for jewelry. Its combination of hardness, lack of cleavage, and good toughness sets it apart from many other gems, including some of its birthstone counterparts.
Key Physical and Chemical Properties
Spinel belongs to the cubic crystal system and has a Mohs hardness of 8, making it resistant to scratching and abrasion. This hardness is surpassed only by a few gems, such as diamond, corundum (ruby and sapphire), and chrysoberyl. Importantly, spinel has no cleavage, meaning it does not have natural planes of weakness along which it can easily break. This, combined with its good toughness, makes it highly suitable for all types of jewelry, including rings and bracelets that are subject to daily wear.
The chemical composition of spinel is MgAl₂O₄, with trace elements such as chromium, iron, and vanadium responsible for its various colors. For instance, chromium imparts red and pink hues, while iron and vanadium can produce blue and violet colors. Spinel has a refractive index of approximately 1.718, which is relatively high, giving it a bright and lively appearance when well-cut. Its specific gravity ranges from 3.58 to 3.61, and it is often isotropic under magnification.
Color and Clarity
One of spinel's greatest attributes is its diverse color palette. It occurs in every color of the spectrum, though some colors are more common than others. Red and blue are particularly common natural colors for spinel, making it an attractive alternative to ruby and sapphire. The red hues can range from a vibrant "ruby-red" to softer pinks, while blue spinel can mimic the appearance of sapphire. Other colors include purple, orange, green, and black. Colorless spinel also exists but is less common.
In terms of clarity, spinel is typically a clean gemstone. It often has fewer inclusions compared to many other colored gems, which enhances its brilliance. When inclusions are present, they are often characteristic of the gem's formation, such as minute crystals or fluid inclusions. The gem's transparency and clarity make it ideal for faceted cuts, which maximize its light performance.
Comparison with Other August Birthstones
To understand spinel's position as an August birthstone, it is useful to compare its properties with those of the other stones associated with the month. Peridot, the traditional modern birthstone for August, is a magnesium iron silicate with a hardness of 6.5 to 7 on the Mohs scale. While peridot is durable, it is slightly softer than spinel and can be more prone to scratches. Sardonyx, a banded chalcedony (a variety of quartz), has a hardness of 7, making it durable but not as hard as spinel. Furthermore, sardonyx is typically cut as cabochons or beads, whereas spinel is often faceted for maximum brilliance.
The table below summarizes the key gemological properties of the three primary August birthstones, based on information from the provided sources:
| Gemstone | Chemical Composition | Mohs Hardness | Common Colors | Typical Cuts |
|---|---|---|---|---|
| Spinel | MgAl₂O₄ | 8 | Red, blue, pink, purple, black | Faceted (brilliant, step) |
| Peridot | (Mg,Fe)₂SiO₄ | 6.5 - 7 | Olive green | Faceted |
| Sardonyx | SiO₂ (Chalcedony) | 7 | Banded white, black, orange, red, brown | Cabochon, beads, cameos |
This comparison highlights spinel's superior hardness and durability among the August birthstones, making it an exceptionally practical choice for jewelry that will be worn regularly.
Symbolism and Metaphysical Beliefs
Throughout history, gemstones have been imbued with symbolic meanings and metaphysical properties. While the provided sources focus primarily on the gemological and historical aspects of spinel, they do touch upon the broader context of birthstone symbolism. The concept of birthstones is rooted in ancient traditions where gems were associated with zodiac signs and calendar months, believed to bring luck, protection, and specific virtues to the wearer.
In modern times, the symbolism of birthstones is often linked to the attributes of the gem itself. Spinel's remarkable durability—its hardness and toughness—can be metaphorically associated with strength, resilience, and endurance. Its wide range of colors, from the passionate red to the serene blue, offers a spectrum of symbolic associations, from vitality and energy to calm and wisdom.
It is important to note that the provided sources do not specify unique metaphysical beliefs or symbolic meanings exclusively attributed to spinel. The information on symbolism in the chunks is more generalized, discussing how birthstones became associated with zodiac signs and calendar months over time. Therefore, any discussion of spinel's specific symbolic properties would be speculative and not supported by the provided materials. The primary significance of spinel as a birthstone, as presented in the sources, lies in its physical attributes and its official recognition on the modern birthstone list, rather than in documented historical lore or metaphysical claims specific to the gem.
Care and Cleaning
The excellent durability of spinel makes it relatively easy to care for and maintain. With a Mohs hardness of 8 and no cleavage, it is resistant to scratching and breaking under normal wearing conditions. This robustness allows it to be set in any type of jewelry, from delicate pendants to heavy-duty rings, without excessive concern for damage.
For cleaning spinel jewelry, standard methods are effective and safe. Warm, soapy water and a soft brush can be used to remove dirt and oils from the surface. Ultrasonic cleaners are generally safe for spinel, but it is always advisable to check the security of the gem's setting before using such devices. Steam cleaning is also typically safe for spinel, but caution is warranted if the stone is set in a mounting that contains other, more delicate gems. It is important to avoid harsh chemicals and sudden temperature changes, which could potentially damage the metal setting or other components of the jewelry.
When compared to other birthstones, spinel's care requirements are straightforward. Gems like opal and turquoise, which are also October and December birthstones respectively, have lower hardness and are more susceptible to scratching and damage. Pearl, a traditional June birthstone, is extremely soft and requires gentle handling. Spinel's resilience means it can be worn daily with minimal maintenance, making it a practical and enduring choice for birthstone jewelry.
Conclusion
Spinel has emerged as a distinguished and valuable addition to the modern birthstone list for August. Its journey from being a historically misidentified gem to a recognized and sought-after birthstone reflects both the advancement of gemological science and the evolving preferences of jewelry consumers. As a gemstone, spinel boasts an impressive portfolio of attributes: it occurs in a vibrant array of colors, most notably in red and blue hues that rival the world's most precious gems; it possesses exceptional durability with a hardness of 8 and no cleavage, making it suitable for all types of jewelry; and it is sourced from diverse geographic locations, each contributing to its color variety.
While the traditional August birthstones of peridot and sardonyx each have their own appeal, spinel offers a unique combination of beauty, durability, and historical intrigue. Its inclusion in the 2016 update to the official birthstone list by the American Gem Trade Association solidified its status as a gemstone worthy of recognition. For individuals born in August, spinel provides a compelling alternative that is both beautiful and practical, capable of withstanding a lifetime of wear. As the gemology community and the jewelry market continue to embrace the full spectrum of gemstones, spinel's star continues to rise, cementing its place as a truly perfect birthstone for the month of August.