The IDIC, standing for Infinite Diversity in Infinite Combinations, is a Vulcan philosophy and symbol celebrating the value of differences.
The IDIC symbol is a circle and triangle joined by a gem, worn as a medallion. It expresses the Vulcan belief that the universe's variety, and the ways differences combine, is to be treasured rather than feared.
Spock wore an IDIC medallion at a dinner held in honor of the telepath Miranda Jones in 2268. The ideal has been invoked many times since as a statement of Vulcan and Federation values.