Ruby gemstones are known for their beauty and the royalty that they bring to the world. Typically red in color, rubies are one of the most popular gemstones. For ages, ruby gemstones have made excellent possessions by gem and jewelry lovers. However, the rising popularity of natural ruby stones made its way to the creation of synthetic rubies in laboratories. In this comprehensive guide, we embark on a journey to unravel the mysteries of synthetic and natural ruby stones, exploring their origins, properties, and significance in the world of gemology.
Understanding Natural Ruby:
Natural rubies are formed deep within the Earth’s crust under conditions of extreme heat and pressure. These geological processes occur over millions of years, resulting in the formation of corundum crystals infused with chromium, which gives rubies their signature red color. The presence of other trace elements can influence the shade of red, ranging from pinkish-red to deep crimson.
Characteristics of Natural Ruby:
1. Origin: Natural rubies are mined from various regions around the world, including Myanmar, Thailand, Sri Lanka, and Africa. Each locality produces rubies with distinct characteristics, such as color, clarity, and fluorescence, influenced by geological conditions and mineral compositions.
2. Inclusions: Natural rubies often contain characteristic inclusions, such as rutile needles, mineral crystals, and tiny fractures known as “silk.” These inclusions, also called “jardin” by gemologists, are indicative of the gem’s natural origin and can affect its clarity and value.
3. Color: The color of natural rubies is typically described using terms like “pigeon’s blood,” denoting a vivid red hue with hints of blue. However, natural rubies can exhibit a range of hues and saturations, from light pink to intense red, depending on factors like chromium concentration and light conditions.
4. Rarity and Value: Genuine natural rubies are rare and highly prized in the gemstone market, commanding premium prices for exceptional specimens with vibrant color, clarity, and size. The scarcity of high-quality natural rubies contributes to their allure and prestige among collectors and connoisseurs.
Unveiling Synthetic Ruby:
Synthetic rubies, on the other hand, are man-made replicas of natural rubies created through various laboratory processes. The first synthetic rubies were produced in the late 19th century, using the flame fusion method developed by French chemist Auguste Verneuil. Since then, advancements in technology have led to the development of several other methods for synthesizing rubies, each with its own advantages and limitations.
Types of Synthetic Rubies:
1. Flame Fusion: The Verneuil process, also known as flame fusion, involves melting aluminium oxide powder (corundum) with chromium oxide to create synthetic ruby crystals. This method produces large, relatively inexpensive rubies with characteristic curved growth lines and gas bubbles under magnification.
2. Flux Growth: Flux-grown synthetic rubies are produced by dissolving aluminium oxide in a molten flux composed of other minerals. This method allows for the control of crystal growth, resulting in higher-quality synthetic rubies with fewer inclusions and improved clarity compared to flame fusion.
3. Hydrothermal: Hydrothermal synthesis involves growing synthetic ruby crystals in a high-pressure, high-temperature aqueous solution containing dissolved aluminium oxide and chromium oxide. This method can produce rubies with excellent clarity and color consistency, closely resembling natural rubies.
Properties of Synthetic Ruby:
1. Composition: Synthetic rubies have the same chemical composition as natural rubies, consisting of aluminium oxide (Al2O3) with trace amounts of chromium responsible for their red colouration. However, synthetic rubies may lack the characteristic inclusions found in natural specimens.
2. Color and Clarity: Synthetic rubies can be produced in a wide range of colors and clarities, depending on the manufacturing process and quality control measures. While some synthetic rubies mimic the vivid red hues of natural rubies, others may exhibit slight variations or fluorescence under ultraviolet light.
3. Affordability: Synthetic rubies are generally more affordable than natural rubies due to their controlled production process and abundance of raw materials. This accessibility makes synthetic rubies a popular choice for jewelry designers and consumers seeking beautiful gemstones at a lower cost.
Visual Similarity and Properties
In the world of gemology, the distinction between natural and synthetic ruby stones is paramount. While both exhibit the captivating allure of deep red hues, their origins and properties vary significantly. Visual similarity often makes it challenging to discern between the two, necessitating a deeper understanding of their inherent characteristics.
Visual Examination:
Visual examination serves as the first step in distinguishing between natural and synthetic ruby stones. While some differences may be subtle to the untrained eye, careful observation can reveal telltale signs indicative of each stone’s origin.
1. Color and Hue:
- Natural rubies often exhibit a vibrant red hue, ranging from pinkish-red to deep crimson. The color is typically caused by trace amounts of chromium within the crystal lattice.
- Synthetic rubies can also display a vivid red color, mimicking natural specimens. However, variations in hue or saturation may occur due to differences in manufacturing processes and impurity concentrations.
2. Clarity and Transparency:
- Natural rubies may contain characteristic inclusions, such as rutile needles, mineral crystals, or “silk” (tiny fractures). These inclusions are evidence of the gem’s natural formation and can affect its clarity.
- Synthetic rubies tend to have fewer inclusions and greater clarity compared to natural rubies. However, some synthetic specimens may exhibit gas bubbles or growth lines specific to the manufacturing method used.
3. Fluorescence:
- Natural rubies often exhibit fluorescence under ultraviolet (UV) light, commonly referred to as “red chalk” fluorescence. This phenomenon is caused by chromium impurities and can aid in distinguishing natural rubies from their synthetic counterparts.
- Synthetic rubies may also fluoresce under UV light, but the fluorescence pattern may differ from that of natural rubies, providing additional clues to their origin.
Physical Properties:
Beyond visual examination, understanding the physical properties of ruby stones can further aid in differentiation. Various gemological tests and measurements can provide valuable insights into a stone’s composition and authenticity.
1. Hardness:
- Both natural and synthetic rubies belong to the corundum mineral species, boasting a hardness of 9 on the Mohs scale. This exceptional hardness makes rubies highly resistant to scratching and suitable for everyday wear.
2. Refractive Index (RI):
- The refractive index measures the speed at which light travels through a gemstone and is a key identifier in gemological testing. The refractive index of ruby ranges from approximately 1.762 to 1.770.
- While the refractive index of natural and synthetic rubies may overlap, variations in other properties can help distinguish between the two.
3. Specific Gravity:
- Specific gravity, or relative density, compares the weight of a gemstone to an equal volume of water. Natural ruby typically has a specific gravity ranging from 3.97 to 4.05.
- Synthetic ruby stones may have a similar specific gravity to natural rubies, but variations in composition or manufacturing processes can lead to slight differences.
Distinguishing Between Natural and Synthetic Ruby:
Identifying the differences between natural and synthetic rubies requires expertise in gemology and specialized equipment, such as microscopes, spectroscopes, and UV lamps. Several key factors can help distinguish between the two:
1. Inclusions: Natural rubies often contain characteristic inclusions, such as rutile needles, mineral crystals, and silk, visible under magnification. In contrast, synthetic rubies may lack these natural inclusions or exhibit different growth patterns and features specific to the manufacturing process.
2. Color and Fluorescence: While both natural and synthetic rubies can display intense red hues, natural rubies often exhibit a fluorescence known as “red chalk” under ultraviolet light, whereas synthetic rubies may show a different fluorescence pattern or none at all.
3. Growth Features: The growth patterns and features observed in rubies, such as curved growth lines, gas bubbles, and color zoning, can provide clues to their origin. Natural rubies typically exhibit irregular growth structures and inclusions, whereas synthetic rubies may display more uniform crystal structures and fewer imperfections.
4. Gemological Testing: Gemological laboratories utilize advanced techniques, including spectroscopy, microscopy, and chemical analysis, to accurately identify the origin of rubies and assess their authenticity. These tests help confirm whether ruby is natural, synthetic, or treated through methods like heat treatment or fracture filling.
Natural rubies embody the timeless beauty of Earth’s geological processes, and synthetic rubies represent human ingenuity and creativity in replicating nature’s wonders. Whether natural or synthetic, the allure of rubies transcends their origins, captivating hearts and minds with their fiery brilliance and enduring charm.
