Assertion: tourmaline's color | /r/HasProperty | unique
Facets:
Source sentences:
text: While iron, manganese, chrome and vanadium are responsible for the coloring in other tourmalines, Paraiba tourmaline is different in that its unique color is owed mostly to the presence of copper.
text: The color of Argyle diamonds is so unique and discernible at first sight to diamond experts that the pink diamonds of that mine have earned their name in the diamond industry under the term Argyle Diamond.