Commercial Bukhara carpets are available in about twenty quality gradations, though surface appearance may be similar. Commercial Bukhara carpets are the best selling hand-knotted rugs in the world. A small tuft of fibers from a rug may be burned to test for its content. For example cotton has a vegetable smell when burned. Wool smells faintly like hair.
Silk smells distinctly like human hair when burned.
The colors of the pre-dyed yarn are chanted rhythmically to assure that rugs are more perfect than rugs made with other techniques. Most fine carpets from Tabriz and Isfahan are made this way. The often derided name for Caucasian type rugs made in Chechnia and Dagistan. The fine whiskers from the chin of sheep that are sometimes set aside a special ceremonial carpet. Chin wool carpets are considered finer than silk ones but are very rare.