The Karateka’s (karate practitioner) belt colour indicates a rank & their ability. As skills & knowledge increase so does a Karateka’s rank.
A Karate Black Belt indicating a rank of first Dan and above wears a plain black cotton or silk covered belt, usually embroidered with the wearer’s name and/or school.
In some Karate Styles, a red belt is worn to denote a very advanced Dan rank.
Officially approved WKF Belts
In modern Karate, as governed by the World Karate Federation and its subsidiary federations, red (aka) and blue (ao) belts are worn by competitors. Only red and blue belts are to be worn for competition, with foot and fist pads of the corresponding colour for kumite competition.