There was an early film made by either the WTF or Kukkiwon from the mid 70's which showed the belt colors as white, yellow, green, blue, red and black, in that order.
The original belt colors of the Chung Do Kwan was white, red and black, which were the original belt colors used at the Shotokan. The Shotokan used white and red because the country at the time when GM Lee was studying was highly nationalistic and in WWII mode, white and red being the colors of the Japanese flag. Brown was later substituted for red by the Shotokan after WWII.
When GM Lee moved back to Korea he used the same color belt system as the Shotokan. In fact, the original Chung Do Kwan curriculum was exactly what GM Lee learned at the Shotokan from his main teacher FUNAKOSHI Yoshitaka Sensei. When you add the blue from the name Chung Do Kwan to the belt colors, you end up with the colors on the Korean flag.
Students would start off as 8th Guep White Belts and then get double promoted to 6th Guep White in six months, then 4th Guep Red Belt in another six months, and so forth. You could make it to 1st Dan at the Chung Do Kwan under GM Lee in two years. One more year, and you would be eligible for 2nd Dan promotion. I have a copy of the original Chung Do Kwan bylaws and it lays everything out, including time in grade promotions up to the rank of 7th Dan, which was the highest back then. Under GM Lee, you could go from 8th Guep white belt to 7th Dan black belt in fifteen years.
