I think you mean "asabache". It is a charm usually found in the shape of a little black ball or tiny black hand, and is worn on a bracelet or necklace.
Most Dominicans are very superstitious, so parents, friends and relatives give an asabache present as a good-luck charm to a newborn baby. Supposedly, this wards off "el mal de ojo" -- the "evil-eye" spell, and protects the child from harm.
-Indie