The enduring appeal of birthstones lies in their blend of beauty, history, and personal significance. However, beyond their aesthetic qualities, the durability of a birthstone—its resistance to scratching and abrasion—is a crucial factor for those considering these gems for jewelry, particularly for everyday wear. This article explores the hardness of birthstones, utilizing the Mohs scale as a benchmark, and provides guidance on appropriate care based on each gem’s inherent resilience.
Understanding Gemstone Hardness
The Mohs scale of mineral hardness, developed in 1822 by German mineralogist Friedrich Mohs, provides a comparative measure of a mineral’s resistance to scratching. The scale ranges from 1 to 10, with 1 representing the softest mineral (talc) and 10 representing the hardest (diamond). A harder mineral can scratch a softer one, but not vice versa. This scale is a fundamental tool for gemologists and jewelry professionals in assessing the suitability of a gemstone for various applications. While hardness is a key indicator of durability, it’s important to note that it doesn’t encompass toughness, which refers to a gem’s resistance to chipping or breaking.
Hardness Across the Birthstone Months
The durability of birthstones varies significantly. Diamond, the April birthstone, reigns supreme with a Mohs hardness of 10, making it exceptionally resistant to scratching and ideal for daily wear. Sapphire, the September birthstone, and Ruby, the July birthstone, closely follow with a hardness of 9, also qualifying them as excellent choices for all types of jewelry. Alexandrite, a June birthstone, registers at 8.5, and Topaz, for November, scores an 8, indicating good durability.
Several other birthstones exhibit moderate hardness. Garnet (January) ranges from 6.5 to 7.5, and Amethyst (February) scores a 7, making them fairly durable. Citrine (November) also has a hardness of 7. Aquamarine (March) falls within the 7.5–8 range, suggesting it is well-suited for regular wear. Tanzanite (December) has a hardness of 6.5. Zircon (December) measures between 6 and 7.5, while Peridot and Spinel (August) range from 6.5 to 8.
However, some birthstones are considerably softer and require more careful handling. Opal (October) has a hardness of 5.5–6.5, and Turquoise (December) falls between 5 and 6. Pearls (June) are the softest birthstone, registering only 2.5 on the Mohs scale. These softer gems are more susceptible to scratches and abrasions and are best suited for pendants, earrings, or occasional wear.
The following table summarizes the Mohs hardness of each birthstone:
| Month | Birthstone(s) | Mohs Hardness |
|---|---|---|
| January | Garnet | 6.5–7.5 |
| February | Amethyst | 7 |
| March | Aquamarine | 7.5–8 |
| April | Diamond | 10 |
| May | Emerald | 7.5–8 |
| June | Pearl | 2.5 |
| June | Moonstone | 6 |
| June | Alexandrite | 8.5 |
| July | Ruby | 9 |
| August | Peridot | 6.5–8 |
| August | Spinel | 6.5–8 |
| September | Sapphire | 9 |
| October | Opal | 5.5–6.5 |
| October | Tourmaline | 5.5–6.5 |
| November | Citrine | 7 |
| November | Topaz | 8 |
| December | Blue Topaz | 5–8 |
| December | Tanzanite | 6.5 |
| December | Turquoise | 5–6 |
Gemstone Care Based on Hardness
The Mohs hardness scale directly informs the appropriate care for each birthstone. Gems with a hardness of 9–10, like diamond and sapphire, require minimal maintenance and are suitable for daily wear. They can be cleaned with warm, soapy water and a soft brush.
Birthstones in the 7–8 range, such as amethyst, aquamarine, and topaz, require moderate care. Avoid exposure to abrasive materials and harsh chemicals. Cleaning can be performed with warm, soapy water and a soft brush, followed by rinsing and drying with a soft cloth.
Softer birthstones (hardness of 5–6.5), including opal, turquoise, zircon, and citrine, demand more delicate handling. These gems should be protected from impacts and scratches. Cleaning should be limited to a soft cloth and mild soap, avoiding ultrasonic cleaners or steam cleaners. Pearls, with their extremely low hardness, are particularly vulnerable and should be wiped clean with a soft, damp cloth after each wearing. Avoid contact with perfumes, cosmetics, and hairspray.
Historical and Cultural Significance
While the focus here is on physical properties, it’s worth noting that birthstones have a rich history steeped in lore and symbolism. Zircon, for example, has been historically found in countries like Canada, Australia, Thailand, Myanmar, Cambodia, and others. Citrine, often referred to as the “merchant’s stone” or “money stone,” is believed to bring prosperity. Turquoise has long been valued for its rarity and is often seen as a symbol of special value and rarity. These cultural associations add to the enduring appeal of birthstones, but should not overshadow the importance of understanding their physical properties for proper care and longevity.
Factors Beyond Hardness
While the Mohs scale is a valuable tool, it’s important to remember that hardness is not the sole determinant of a gemstone’s durability. Other factors, such as cleavage (the tendency of a crystal to break along specific planes), brittleness, and crystal structure, also play a role. Emerald, for instance, while having a hardness of 7.5–8, is known to be brittle and prone to inclusions, requiring careful handling.
Furthermore, the cut of a gemstone significantly impacts its brilliance and overall appeal. A poorly cut stone, regardless of its quality, will not allow light to pass through and reflect its beauty effectively. The carat weight also influences the price, with larger stones being rarer and more valuable.
Conclusion
The world of birthstones offers a captivating blend of beauty, history, and symbolism. Understanding the hardness and durability of each gem, as measured by the Mohs scale, is essential for ensuring its longevity and preserving its luster. By selecting a birthstone appropriate for the intended use and providing proper care based on its inherent properties, one can enjoy its radiant beauty for generations to come. The enduring popularity of birthstones, despite evolving trends, underscores their timeless appeal and continued relevance in the realm of jewelry and personal adornment.