Assertion: asterism | /r/HasProperty | the star effect
Facets:
Source sentences:
text: These are gems that exhibit special optical phenomena, including asterism (the star effect), chatoyancy (the cat's eye effect), adularescence (shimmering light) and iridescence (the rainbow effect).
text: Asterism (the star effect) is an example of an optical effect found very rarely in a small number of gem types cut as cabochons.