1. A fog proof watch crystal for the replacement of ordinary crystals in watch case bezels, comprising in combination, an outer wall and an inner wall, said walls being spaced equal distance apart except at their peripherial edges which are integrally formed together by means of an interconnecting narrow edge wall there between, a central space thus formed between said walls carrying a gas of a non-moisture nature said peripherial edge additionally having an annular and protruding lip there around for being received within a watch case bezel in order to retain said crystal within said watch, jewels and the like being located within and secured in the hermitically sealed space defined between said walls, said jewels serving as decorative numerical characters for telling time, and said hermitically sealed space forming an insulation barrier to prevent condensation on an underside of said crystal.