Assertion: opal | /r/HasAspect | great importance
Facets:
value: in ancient times
type: TEMPORAL
value: because of its colorful play of colors
type: CAUSE
value: as a gem
type: OTHER
Source sentences:
text: The Opal has a great importance as a gem – because of its colorful play of colors, which is often blue-green.
text: In ancient times, the opals had a great importance, and they were rated even higher than diamonds.