Black horn 10 mm coin. Black horn is the natural color of horn from a water buffalo locally know as carabao in the Philippines. Pieces are hand cut into squares and individually drilled with a hole, strung and shaped. The black horn has a natural whitish streak to it so you cannot expect all the beads to be solid black. Because of the natural luster when polished, horn is a very versatile component used to incorporate with different types of materials in jewelry. Note that the horn is a byproduct of the food industry.