What is Geuda primarily known for?

Geuda is primarily known for being a type of corundum that can undergo treatment processes to achieve a desirable blue color, which is highly valued in the gemstone market. Initially, geuda stones are often light-colored or have an undesirable hue; however, through treatment methods such as heat treatment, these stones can be transformed into beautiful blue sapphires. This process enhances their appeal and market value, leading to their recognition as gemstones in the industry.

In contrast, the other options do not accurately represent geuda's characteristics or uses. Geuda is not recognized as a precious gemstone without treatments; it is not a synthetic corundum; and it is not exclusively used for industrial purposes, as it can be enhanced to serve as a gemstone in jewelry.