COLOR

Trasparent gems, in contrast, transmit as much light as possible or through the stone. Theirs is a multidimensional loveliness accounts for the reason why some gems, like diamonds, are also highly prized. Tnsparency, regardless of color (rubies and sapphires are also transparent), has certain characteristics of it is own. One accounts for that fire and is known as fire as well as dispersion.

A gem, no matter transparent, is a solid mass. As a result, light passing through it is bent or refracted. Since each color-and even "white" light is composed of all colors in the spectrum-is refracted differently according its own intensity, the result of light falling on a gem is a colors or fire. The light, in other words, is dispersed into its inclusions affect dispersion, since they distort light and may even dispersion to a lesser or greater degree, depending on and number of the inclusions.

Different gems disperse light differently. Diamonds are particularly for their fire. They have a high dispersion characteristic. A as on the other hand, quartz has low dispersion characteristics. As a result, no rock crystal (a form of quartz often used to substitute for diamonds) will ever have the fire of a diamond with top clarity.

Two other terms are also sometimes used and may be confused with fire. One is brilliance. When you look into a diamond, for instance, you see internal reflections of white light from deep inside it as well as external reflections from the highly polished hard surface. Brilliance refers to these internal reflections. Again, the fewer and tinier the inclusions, the more brilliant the stone will be. The other term is scintillation. Diamonds and other gems are cut with a multitude of faces or facets (see "Facet Cuts" below). Scintillation is the twinkling or flashing caused by light striking the facets as you move your eyes or as the source of light is moved.

Some gems exhibit another characteristic in light. These gems act as a filter, screening out various colors of light. A white diamond appears white because all light passes through. When only a certain color in light is transmitted, the gem will appear to be that color. Sometimes, two colors appear, depending on the direction of the light and the way the gem is turned. Such gems are said to be dichroic, showing two colors. More rarely, three colors can be seen, making the gem trichroic, showing three colors. The phenomenon of different colors appearing in the same gem is also known as pleochroism, meaning the ability to show several colors.