Black raisins are an organic raisin with a dark skin. They are usually made from plums, prunes, or a mix of these two fruits. Black raisins are an organic raisin with a dark skin. They are usually made from plums, prunes, or a mix of these two fruits. Raisins are dried grapes that have been sun-dried and crushed into a hard, wrinkled, dark purple-black. The fruits flesh is then removed and the seed is left behind, which is where the raisin gets its name from.