Patent ID: 7465421

Claim:
A process for preparing a fire opal for use in jewelry and ornaments, the process comprising the steps of: a. mixing at room temperature and atmospheric pressure ethanol, nitric acid, distilled water, and at least one inorganic salt colorant, to obtain a homogeneous reaction mixture; b. adding tetraethylorthosilicate (TEOS) to this homogeneous reaction mixture to obtain a clear sol; c. gelating the clear sol at room temperature to obtain a gel; d. drying the gel at temperatures ranging from 50° C. to 100° C. to obtain a colored and transparent material; and, e. sintering the dried gel at temperatures ranging from 250° C. to 800° C. to remove the organic part of the colored and transparent material in order to obtain a uniformly colored, silica matrix which is transparent and hard.