The term for the degree to which a substance such as porcelain or glass allows light to pass though it (thickness permitting) and the quality or colour of that light on passing out of the body. Found on http://www.encyclo.co.uk/visitor-contributions.php
translucency Translucent materials which allow light to pass through them in a diffuse manner; that is, the material's translucency distorts the image. Although transparency usually refers to visible light in common usage, it can actually refer to any type of radiation; for example, bodily flesh is transparent to X-rays, while bone is not. ... Found on http://www.wordinfo.info/words/index/info/view_unit/1212/7