#gemystique
Where synthetic gems can be grown in a number of different processes and methods, synthetic corundum is primarily grown by two processes. It is either grown by a melt process or a solution process. Melt process consists of methods like Flame Fusion-Verneuil, Pulling-Czochralski, Skull and Floating Zone, while the solution process has the Flux and Hydrothermal methods.
Melt process synthetics, namely flame fusion synthetics are more commonly found as it is a low cost and high-volume method, hence produced in large numbers.
Among other characteristics found in flame fusion synthetics, perhaps the most diagnostic is its curved growth. This is either visible as curved striae or curved color banding, depending on the color of the synthetic produced. The two can also be observed together occasionally.
Blue flame fusion sapphires often exhibit curved color banding however it is not always easily spotted. In fact, sometimes it can be pretty tricky as the color bands are very faint. Best method to observe this feat is by examining the stone under diffused transmitted illumination while adjusting the brightness. Often, the banding becomes more prominent as the brightness is reduced. Equally important is to examine the stone in various multiple directions.
Photomicrographs attached show a striking display of how easily this feature can be overlooked if the proper illumination conditions are not used and also if the stone is not observed in various positions. Curved banding in this stone becomes visible at various positions as the stone is tilted slightly.
Sheikh Fahad Abbas – GIA GG, AJP
Founder & Owner – Gemystique®
