Assertion: black onyx | /r/CapableOf | use as the background material
Facets:
Source sentences:
text: In addition, so-called marketplace black onyx is currently used in all sorts of jewelry, usually as cabochons or beads or other rounded forms, but also, albeit infrequently, faceted; and, it has been carved, currently usually employing laser techniques, or used as the background material for inlays of materials such as opal.