Assertion: black opal | /r/HasProperty | rare
Facets:
value: very
type: DEGREE
Source sentences:
text: Black opal, with a very dark gray or blue to black body colour, is particularly rare and highly prized.
text: Black opals are very rare and therefore the most valuable.
text: Black Opal, with a very dark gray or blue-to-black color, is rare and highly prized.