Synthetic star sapphires were first produced in the late 1940s by Linde Co. Ltd., its special star effect (asterism) immediately became a huge sensation at the time, it was so popular, some still call synthetic Star Sapphire stone “Linde Star.”
In 1979, Durable Star Co., Ltd. study the technique from the USA and Japan enhanced it by exploring finer formula and better crystal growth. After many research and experiment, Durable Star discovered that using Verneuil flame fusion to melt dopped alum and titanium oxide could with right calculation could create best synthetic star sapphire and star ruby.
Star sapphire and star ruby value depend on the clarity of the star. The gemstones must be evaluated using a single source of light such as a sunlight or spotlight, it is difficult to see a clear star under fluorescent light.