Leakage
leak·age | ˈlē-kij
noun
The leaving or escaping of light through the facets of fashioned gemstones
Leakage is a term often used to describe the way in which light flows through a fashioned gemstone, diamonds in particular. Leakage occurs when light enters a polished stone, moves around inside the gemstone, and then exits the stone again in another direction. Leakage is often devised intentionally to improve the brilliance and ensure the diamond sparkles more readily under light. Diamond cuts are designed to maximize the refraction of white light and colored light, and the leakage is a byproduct of these cuts. Each type of cut will result in a different direction for the leakage, and there is bad leakage, which involves light being lost out of the bottom of the stone.