I found this simplified Stober method and was wondering if you chemists out there could comment on whether this would work or not to produce a difracting layer of opal? Also wondering if such chemicals as TEOS could be obtained by me (an average non chemist) so I could try making some opal in my home lab? If so, then where could I get some? and would household amonia work vs. anhydrous amonia? For the first solution Add 12-17 parts of tetraethyl orthosilicate (TEOS) to 100 parts of alcohol (ethanol) with stirring. For the second solution Add 30-50 parts of ammonium hydroxide to 250 parts of alcohol. Next: Add the TEOS/alcohol solution to the ammonia/alcohol solution slowly with stirring. Continue stirring for about an hour to allow the reaction to come to completion. Depending on the exact concentrations of reagents you will generate a milky suspension of 250-400 nanometer silica spheres. Pour the suspension into a tube and allow it to settle. A thin layer of opal color will form in a few days and within 2-3 weeks all the suspension will have settled out and formed a brightly diffracting layer of "opal" usually a few millimeters thick depending on how much solution and the size and shape of the container. You can continue to make new batches and add to the container to increase the thickness of the growing opal layer.