All crystals, whether formed deep within the Earth or in a laboratory, share the fundamental characteristic of having an ordered, repeating atomic structure. This precise, geometric arrangement of atoms defines a crystalline solid and grants it distinct physical properties. Humans have developed methods to recreate the pressure and heat required to form these materials, resulting in what are broadly termed man-made crystals. These materials are synthesized in controlled factory or laboratory environments to meet the demands of the jewelry market and specialized industries.
The Difference Between Natural and Synthetic
Understanding the terminology used to describe man-made crystalline materials is important for the consumer. A synthetic crystal is chemically and structurally identical to its natural counterpart; the only difference is its origin. A synthetic ruby, for instance, possesses the exact same aluminum oxide composition and hexagonal crystal structure as a mined ruby, having been grown in a lab over days or weeks instead of millions of years.
A simulated material or simulant, however, is an imitation that looks similar to a natural crystal but possesses a different chemical composition and atomic structure. Common simulants, such as glass or plastic, are often used to mimic the appearance of more expensive gems. The distinction between a synthetic material and a simulant is significant for correctly assessing material properties like hardness and durability.
Common Synthetic Gemstones
The jewelry market features several popular man-made materials that replicate or simulate high-value natural stones. One of the most widely used simulants is Cubic Zirconia (CZ), a hard, colorless material synthesized from zirconium dioxide. CZ is commonly used as an affordable simulant for diamond, but it is not chemically related to carbon, the sole element of a true diamond.
Another popular diamond alternative is synthetic Moissanite, which is composed of silicon carbide. While naturally occurring moissanite is extremely rare, the synthetic version is routinely grown in laboratories. It exhibits a brilliance and fire that often exceeds that of a diamond, and its high hardness makes it very durable for everyday wear.
Lab-grown corundum, which includes synthetic rubies and sapphires, is chemically identical to the natural mineral aluminum oxide (\(\text{Al}_2\text{O}_3\)). These are frequently produced using methods like the Flame Fusion (Verneuil) process, which melts aluminum oxide powder and allows it to recrystallize quickly. Similarly, lab-grown diamonds are pure carbon crystals that are structurally identical to mined diamonds, typically created using High-Pressure/High-Temperature (HPHT) or Chemical Vapor Deposition (CVD) techniques.
Industrial and Scientific Synthetics
The synthesis of crystals extends far beyond jewelry production, fulfilling critical needs in modern technology. Synthetic quartz, composed of silicon dioxide, is grown in massive quantities for its piezoelectric properties. This means it generates an electric charge in response to mechanical stress, making it indispensable for use in electronic oscillators, filters, and high-precision timing devices. The hydrothermal method is often used, dissolving silica in a high-pressure, high-temperature water solution to grow large, pure crystals.
Silicon wafers, which form the foundation of almost all modern microelectronics, are another example of a foundational man-made crystal. These are grown as large, single-crystal ingots of silicon and then sliced into thin wafers for semiconductor manufacturing. Specialized materials, such as Gallium Nitride and ceramic crystals, are synthesized for advanced applications like high-power electronics, laser technology, and complex optical systems. These processes allow for a level of purity and structural consistency often unobtainable in naturally occurring mineral deposits.
Identifying Man-Made Crystals
Distinguishing a man-made crystal from a natural one often relies on examining subtle internal characteristics left by the growth process. Natural crystals typically contain random inclusions, such as tiny trapped minerals or irregular growth zones, which act as a geological fingerprint. Synthetic materials, particularly those grown rapidly from a melt, can exhibit tell-tale signs like internal curved growth lines, a direct result of the laboratory method.
Another common indicator of a man-made material, especially in simulants like glass, is the presence of small, rounded gas bubbles trapped within the structure. Synthetic gems often display a color consistency that appears unnaturally uniform or saturated. While basic simulants may be identified by differences in hardness or light refraction, more sophisticated synthetics often require advanced testing by a gemologist to confirm their origin.