society > occupation and work > materials > raw material > gem or precious stone > diamond > 			[noun]		 > fine or perfect diamond (4)		
Originally: a perfect diamond (also figurative). Now: spec. one weighing more than 99 carats. Also more fully †paragon stone.
A diamond of the finest cut and brilliancy.
A diamond which is flawless or lustrous in its natural state.
The finest grade of diamond. Cf. river stone n. at compounds 3, and water, n. 28.