A synthetic ruby is a gemstone created in a laboratory, possessing the identical chemical composition, crystal structure, and physical properties as its naturally occurring counterpart. Both are composed of aluminum oxide (Al₂O₃) with a small amount of chromium, which imparts the gem’s characteristic red color. These man-made rubies are not imitations or simulants; they are genuine rubies, differing only in their origin. Simulants, in contrast, merely mimic a ruby’s appearance but lack its inherent properties, such as hardness or refractive index. Understanding synthetic rubies and their production highlights their significance in various fields, from industrial applications to jewelry.
Methods of Creation
The creation of synthetic rubies involves several laboratory techniques, each designed to replicate the natural growth process under controlled conditions. The Verneuil method, also known as flame fusion, is the oldest and most widely used technique, first enabling mass production in the early 20th century. In this process, finely powdered aluminum oxide mixed with chromium oxide is dropped through an oxyhydrogen flame. The intense heat melts the powder, and the molten droplets fall onto a rotating pedestal, gradually forming a single, teardrop-shaped crystal known as a boule.
Another technique is the Czochralski method, a melt process where a seed crystal is slowly pulled from a molten bath of the ruby’s constituent elements. As the seed is rotated and withdrawn, the ruby material crystallizes onto it, forming a large, high-quality crystal. Both the Verneuil and Czochralski methods efficiently produce substantial synthetic ruby crystals, often with characteristic internal features.
Solution growth methods, such as flux growth and hydrothermal growth, offer alternative approaches. Flux growth involves dissolving the ruby’s components in a high-temperature chemical solvent, or flux. As the solution slowly cools, ruby crystals precipitate and grow, often yielding crystals with fewer internal stresses and different inclusion patterns compared to melt processes.
The hydrothermal growth method simulates the Earth’s natural conditions by growing rubies from a superheated aqueous solution under high pressure. This technique is more complex and time-consuming but can produce crystals that closely resemble natural rubies, including some types of inclusions. Each method offers distinct advantages in crystal quality, size, and internal features.
Telling Them Apart
Distinguishing synthetic rubies from their natural counterparts often requires careful examination by trained gemologists using specialized equipment. While both share identical chemical and physical properties, their internal characteristics, shaped by their formation environment, differ in subtle yet important ways. These internal features, visible under magnification, serve as key identifiers.
Synthetic rubies produced by the Verneuil or Czochralski melt methods exhibit curved growth lines, known as curved striae, which are never found in natural rubies. Tiny, spherical or elongated gas bubbles can also be present within these melt-grown synthetics, remnants of the high-temperature fusion process. These distinct internal markers provide clear indications of a laboratory origin, making identification possible for experts.
Rubies grown through solution methods, such as flux growth or hydrothermal growth, show different types of inclusions. Flux-grown synthetic rubies can contain remnants of the flux material itself, appearing as wispy “fingerprint” patterns or tiny platinum crystals from the crucible. Hydrothermal rubies may also display unique “fingerprint” inclusions or subtle growth zoning, reflecting their slower growth.
In contrast, natural rubies contain inclusions formed during their geological formation. Common natural inclusions include fine, needle-like rutile crystals, often called “silk,” or various other mineral crystals. Natural rubies also display angular growth zoning, reflecting varying conditions during their crystallization within the Earth’s crust. While some synthetic rubies are grown with inclusions to imitate natural ones, the specific patterns and types of inclusions remain distinct upon expert examination.
Beyond Jewelry: Their Uses
Beyond their aesthetic appeal in jewelry, synthetic rubies are valuable in numerous industrial and technological applications. Their hardness, ranking 9 on the Mohs scale, combined with chemical inertness and thermal stability, makes them suitable for demanding environments, performing reliably under high temperatures and pressures.
One historically significant application is in laser technology. The first successful laser, developed by Theodore Maiman in 1960, utilized a synthetic ruby rod to produce a coherent beam of deep red light at 694.3 nanometers. Today, ruby lasers are employed in medical aesthetics for procedures like tattoo removal, optical research, and industrial processes such as cutting and welding.
Synthetic rubies also find use in precision instrumentation, particularly as low-friction bearings in mechanical watches and other delicate mechanisms, for wear resistance. Their durability ensures longevity and accuracy in these applications. Their excellent optical properties, including high transparency and specific light absorption and emission, make them valuable components in various optical and medical devices requiring precise light manipulation.
Market Value and Considerations
The market value of synthetic rubies differs substantially from that of natural rubies, despite their identical chemical and physical properties. Due to their laboratory origin and large-scale production, synthetic rubies are significantly more affordable, often costing 95% to 99% less than comparable natural stones. This accessibility makes the beauty of ruby available to a broader range of consumers who might otherwise find natural rubies cost-prohibitive.
Sellers in the gemstone industry are expected to clearly disclose whether a ruby is natural or synthetic. This transparency is important for consumer confidence and allows buyers to make informed decisions based on their preferences and budget, ensuring ethical transactions. While synthetic rubies offer durability and visual appeal at a lower price point, natural rubies retain higher value due to their rarity and unique geological formation, perceived as a finite resource.