How are natural gemstones treated to reval color or elimate flaws?

Natural gemstones are often treated to enhance their color or eliminate flaws through various methods. Common treatments include heat treatment, which can improve color and clarity, and dyeing, which adds color to more porous stones. Additionally, some gemstones undergo oiling or resin filling to conceal surface cracks and enhance overall appearance. These treatments can significantly affect the gemstone's value and marketability.