Faceting is the art of cutting & polishing a transparent stone at definite angles so that it sparkles.
Materials other than transparents are also faceted & some coloured stones (such as emerald & ruby) are cut more for colour enhancement than for brilliance.
Many stones exhibit colour bands or zones & some will show different colours when viewed on different crystal axes. This, plus the precission required, make faceting a difficult but rewarding hobby.
Our club has an air-conditioned faceting room with 5 machines & cources from beginners through intermadiate to advanced are held throughout the year.