In natural stones cracks are found, in these cracks, oil is filled. If the gem is colored then colored oil is filled, and if the gem is transparent, then colorless oil is filled. With this oiling; the beauty of the gemstone increases along with its value. Indeed, this oil does not remain in the stone for a longer period. The customer uses the gemstone in finger rings or another jeweler, due to its regular use, the oil used in the gemstone oozes out, thereby the luster and the color of the stone becomes faded making its cracks visible. It's ridiculous to note that seeing these cracks superstitious comments that, "The cracks are the signs indicating about the problems that were to come upon you but has been an obstacle by the stone."

Certain gemstones are heated and their beauty increases so the impurities in them are reduced. Such gemstones are called, 'heat-treated gemstones.' This treatment is usually done on ruby and sapphire. Similar to heat treatment some gemstones are radiated and made beautiful, such gemstones are called radiated gemstones. This treatment is done in Topaz.