What Is A Lab Created Sapphire - T-Tees - Your Answers Await, Life's Questions Unraveled

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790-ct synthetic sapphire - lab-grown sapphires — This 790-ct sapphire was cut from colorless corundum grown via the Czochralski (melt) process. In the 1970s, manufacturers grew immense lab-grown sapphires for a variety of applications. They cut this melt material into large, thick rectangular slices to make windows for helicopter gunships. The physical properties of sapphire could blunt the tips of incoming rounds, preventing penetration into the aircraft. Photo © Joel E. Arem, PhD, FGA. Used with permission.

How are Lab-Grown Sapphires Made?

Whether under the Earth or in a laboratory, crystal gemstones develop or “grow” when the right combinations of minerals interact under specific chemical and physical conditions. Of course, the chief advantages of synthesizing gems in a laboratory (from the manufacturer’s perspective) are time and financial savings. In a lab, manufacturers can control and even accelerate chemical and physical processes as well as combine minerals that occur rarely in nature. In effect, labs can create to order gems difficult or expensive to mine.

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Synthetic star rubies and sapphires — All gem varieties of corundum can be synthesized through various methods, including the coveted “star stone” sapphires and rubies, such as these “Heller Hope” star gems. Photo © Joel E. Arem, PhD, FGA. Used with permission.

There are two types of methods for artificially creating sapphires: melt processes, which involve melting aluminum oxide into a sapphire droplet, and solution processes, which grow sapphire crystals in a solution.

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Melt Processes

The most inexpensive and oldest melt process is known as flame fusion. In this method, a flame melts aluminum oxide powder (the principal mineral in corundum). The drops form into a long teardrop shape called a “boule.” The addition of other minerals to the aluminum oxide can create colored varieties of sapphire. Also, adding chromium to the aluminum oxide will create synthetic ruby.

Solution Processes

Hydrothermal synthesis is a solution process that closely mimics natural formation, subjecting the minerals to intense heat and pressure in a sort of “pressure cooker.” Sapphires form around a seed crystal as the mineral solution rises to the top of the cooker.

Chatham sapphires, like these, are created via a flux solution method. Hexagonal crystal approximately 3 inches across. Photo © Joel E. Arem, PhD, FGA. Used with permission.

Are Lab-Grown Sapphires Really Sapphires?

Chemically and physically speaking, the same materials constitute natural and lab-grown sapphires, and they have the same atomic structure and crystal habit. Gemology labs would identify both lab-grown and natural sapphires as forms of corundum.

How Can Gemologists Distinguish Lab-Grown Sapphires From Natural Sapphires?

Distinguishing lab-grown sapphires from natural sapphires is challenging, but each artificial creation method leaves telltale signs that an expert gemologist can identify.

Melt processes like flame fusion may create sapphires that exhibit curved growth lines and curved color bands not found in nature. The Czochralski process also may produce gems with inclusions like gas bubbles and smoky veils. Hydrothermal synthesis may leave distinctive “nail head” inclusions.