The three main types of caviar are beluga , osetra and sevruga .
Caviar production is a major industry for both countries.
It can range in color from pale silver-gray to black. Next in quality is the medium-sized, gray to brownish gray osetra, and the smaller, gray sevruga caviar. The small, golden sterlet caviar is so rare that it was once reserved for Russian czars, Iranian shahs and Austrian emperors. Caviar is extremely perishable and must be refrigerated from the moment it's taken from the fish to the time it's consumed. Pasteurized caviar is roe that has been partially cooked, thereby giving the eggs a slightly different texture.