The dried reddish orange, threadlike filaments, called stigmas, of a special variety of purple crocus. Saffron threads are used as a spice, and they impart a bright yellow color, bittersweet flavor and exotic aroma food preparations. Because the delicate filaments must be carefully picked by hand, saffron is the world's most expensive spice. There are only three filaments per flower, and it takes at least 225.000 filaments to make a half a kilo of saffron. Saffron is sold in tiny strands called threads and as a powder. Kozani is among the few places in the world that cultivate saffron.