Meijin Colored Karate Belt.

According to the Kodokan Judo Academy in Tokyo, the history of coloured belts for different grades or ability levels was started by Jigoro Kano (1860 -1938) Sensei, the founder of modern Judo.
Kano Sensei, in his youth, studied Kito-Ryu jujutsu. Later, by absorbing techniques from other schools such as Yoshin Ryu, he created Judo (柔道) as a physical activity for all people, from Yawara, the ancient samurai unarmed method of violently subduing an enemy.
When he was a student, instructors wore strong jackets decorated with diagonal lines of stitching similar to a modern kendo jacket. The colour and sometimes the degree of elaboration of the stitching would distinguish the instructors rank and experience.
Kanos idea was to create an art that everyone could practise regardless of income, social status, or gender. Buying expensive new training jackets at every promotion was beyond many people, so he substituted a coloured belt to denote the wearers ability.
Originally just white, brown and black were used; other colours were added as student numbers increased exponentially with the introduction of Judo into the Japanese educational system.
In the early 1920s, when Gichin Funakoshi started introducing Okinawan karate into Japan, Kano Sensei supported him by giving Funakoshi access to the upper levels of Japanese society. Funakoshi adopted both the training clothes of Judo and their coloured belt rank system, thinking, perhaps, that this would allow him to benefit from the prestige of Judo and its founder, who by this time was heavily involved in the Japanese Olympic movement. Time has proved him correct!