The date of July 20th occupies a unique position in the birthstone tradition, bridging the astrological signs of Cancer and Leo. This transitional nature is reflected in the gemstones associated with the date, offering a choice between two distinct yet historically significant stones: the vibrant red Ruby and the grounding black Onyx. While Ruby stands as the official modern birthstone for the month of July, Onyx serves as a powerful alternative, each carrying a legacy of lore, distinct geological origins, and specific gemological properties. This article provides a comprehensive exploration of these two gemstones, examining their historical roots, physical characteristics, and enduring significance for those born on this day.
Historical Roots and Cultural Significance
The tradition of birthstones finds its earliest roots in the biblical description of the High Priest Aaron’s breastplate, which featured twelve precious stones representing the tribes of Israel. Over centuries, this concept evolved, intertwining with zodiacal associations and cultural beliefs that attributed protective and healing properties to specific gems. For July 20th, the birthstone tradition is particularly rich, reflecting the duality of the date itself.
Ruby, the official July birthstone, has been revered across civilizations for millennia. In ancient India, it was acclaimed as the "king of precious stones," a title earned through its rarity, exceptional hardness, and intense red color. This crimson hue was deeply associated with life force and blood, making Ruby a symbol of power, passion, and youthful energy. Its lore extends to the Burmese, where warriors believed the gemstone could grant invincibility in battle. The gem’s journey to becoming a modern birthstone was solidified in the 20th century when organizations like the American National Retail Jewelers Association (now Jewelers of America) standardized birthstone lists, selecting Ruby for July due to its enduring appeal and desirability in the jewelry market.
In contrast, Onyx has a different but equally compelling history. As a banded form of chalcedony, Onyx has been valued since antiquity for its grounding properties. Ancient Greeks and Romans utilized Onyx in amulets and talismans, believing it could ward off negative energies and provide stability. While not the official birthstone for July, Onyx appears as a significant alternative, particularly in systems that consider the specific date or zodiacal cusp. The association of Onyx with July 20th may also stem from the date’s position within the Cancer sign, for which Onyx is sometimes listed as a traditional or alternative gemstone. This dual heritage allows those born on July 20th to choose a gemstone that resonates with either the fiery passion of Ruby or the protective stability of Onyx.
Geological Formation and Global Sources
The formation of these gemstones is a testament to the diverse processes of the Earth’s geology. Ruby, a variety of the mineral corundum, is composed of aluminum oxide (Al₂O₃) with trace amounts of chromium responsible for its signature red color. The intensity of the red is directly correlated with the chromium content. Ruby forms under high-temperature and high-pressure metamorphic conditions, typically found in marble deposits or in silica-poor igneous rocks. Historically, the most prized rubies have come from the Mogok region of Myanmar (Burma), known for producing gems with a vivid "pigeon’s blood" color—a deep red with a subtle violet undertone. Other significant sources include Vietnam, which has emerged as a major producer of high-quality rubies, and Sri Lanka, known for its lighter but still vibrant red gems. In recent years, East Africa, particularly Mozambique and Tanzania, has also become an important source of commercial-quality rubies.
Onyx, on the other hand, is a cryptocrystalline form of quartz, specifically a variety of chalcedony. Its characteristic black color and parallel bands are formed through the deposition of silica in gas cavities within volcanic rock, a process that creates layers of different impurities. Unlike Ruby, Onyx is found in a wide range of locations globally. Major sources include Brazil, India, Uruguay, and parts of the United States (such as Arizona and Oregon). The banded variety of Onyx, often featuring alternating black and white layers, is particularly sought after for use in cameos and intaglios. While Onyx is more abundant and less expensive than Ruby, its unique banding and deep black color make it a valued gemstone in its own right.
Gemological Properties and Identification
Understanding the physical properties of Ruby and Onyx is essential for identification, valuation, and proper care. The following table summarizes key gemological data for both stones, based on standard gemological references.
| Property | Ruby (Corundum) | Onyx (Chalcedony) |
|---|---|---|
| Chemical Formula | Al₂O₃ (Aluminum Oxide) | SiO₂ (Silicon Dioxide) |
| Crystal System | Trigonal | Trigonal (microcrystalline) |
| Hardness (Mohs Scale) | 9 | 7 |
| Specific Gravity | 3.95 - 4.10 | 2.65 - 2.91 |
| Refractive Index | 1.762 - 1.770 | 1.53 - 1.54 |
| Luster | Vitreous (glass-like) | Vitreous to waxy |
| Typical Color | Red (due to chromium) | Black (carbon/iron oxide), often banded |
Ruby: The King of Gems Ruby’s most critical characteristic is its color. The finest color is described in the trade as "pigeon’s blood," a deep, pure red with a slight purplish undertone. Clarity is also a major factor; while inclusions are common in natural rubies, the most valuable stones are those with high clarity and transparency, though some inclusions can enhance the stone's color saturation. Ruby’s exceptional hardness (9 on the Mohs scale) makes it one of the most durable gemstones, second only to diamond. This durability means ruby jewelry is well-suited for daily wear, as it resists scratching and abrasion. However, like all gemstones, it can be chipped or fractured by a sharp blow due to its cleavage properties.
Onyx: The Grounding Stone Onyx is prized for its deep, uniform black color and its characteristic banding. The most valuable form is solid black Onyx, though banded Onyx (often with layers of black and brown) is also popular. With a hardness of 7 on the Mohs scale, Onyx is durable enough for most jewelry applications but is more susceptible to scratching than Ruby. It has no cleavage, making it resistant to breaking along planes, but it can be brittle. Onyx is typically cut into cabochons (smooth, rounded domes) to highlight its color and banding, though it can also be faceted. Its lower refractive index compared to Ruby gives it a more subdued luster.
Symbolism and Metaphysical Beliefs
The symbolic meanings attached to Ruby and Onyx are as distinct as their colors. These beliefs, rooted in ancient lore and continued in modern crystal healing practices, offer additional layers of significance for the July 20th birthstone.
Ruby is universally associated with passion, love, and vitality. Its red color is linked to the heart and blood, symbolizing courage, strength, and emotional intensity. In Hindu tradition, Ruby is considered a stone of the Sun, representing power, leadership, and success. It is believed to stimulate the root and heart chakras, fostering confidence and overcoming lethargy. For those born on July 20th, wearing Ruby is thought to enhance personal power, attract love, and protect against negative emotions.
Onyx, conversely, is revered as a stone of protection and grounding. Its black color is associated with the earth and the night, symbolizing stability, endurance, and self-control. Historically, it was used to ward off evil spirits and negative energy. In metaphysical practices, Onyx is believed to absorb and transform negativity, making it a powerful tool for emotional balance and stress relief. It is associated with the root chakra, promoting a sense of security and resilience. For individuals born on the Cancer-Leo cusp, Onyx can offer a stabilizing influence, helping to anchor the emotional depth of Cancer with the confident energy of Leo.
Care and Cleaning
Proper maintenance ensures the longevity and beauty of both Ruby and Onyx jewelry. Their differing hardness and chemical composition require specific care methods.
Ruby Care: Due to its high hardness, Ruby is relatively easy to care for. It can be cleaned using warm water, mild soap, and a soft brush. Avoid harsh chemicals, such as chlorine or bleach, which can damage the stone or its setting. Ultrasonic and steam cleaners are generally safe for Ruby, provided the stone is not heavily included or fracture-filled. However, if the Ruby has been treated (e.g., with lead glass filling), these methods may not be advisable. Store Ruby jewelry separately to prevent scratching other softer gems.
Onyx Care: Onyx, with a hardness of 7, requires slightly more caution. It should be cleaned with a soft, damp cloth and mild soap. Avoid harsh chemicals and acids, which can etch the surface. Ultrasonic cleaners are not recommended for Onyx, as the vibrations can cause damage, especially if the stone has fractures. Steam cleaning is also discouraged due to the risk of thermal shock. Store Onyx away from harder stones to prevent scratches. Given its relative softness, Onyx jewelry is best suited for occasional wear rather than daily use, particularly for rings and bracelets that are prone to impact.
Conclusion
The birthstones for July 20th—Ruby and Onyx—offer a compelling study in contrasts: one a fiery symbol of passion and power, the other a grounding force of protection and stability. Ruby, the official July birthstone, captivates with its intense red hue, legendary hardness, and historical status as the "king of gems." Onyx, as a significant alternative, provides a sleek, protective presence valued since antiquity. For those born on this transitional date, the choice between these two stones allows for a personal expression that aligns with either the vibrant energy of Leo or the nurturing depth of Cancer. Both gemstones, with their rich histories and distinct properties, remain timeless treasures, continuing to inspire and adorn across generations and cultures.