I have a case Cheetah #6111 1/2L from the 60's when I was a teenager. I have tried to look up the value, but value goes by dates , color and pattern numbers from what I can see. I also do not know the difference between red bone and pretty bone which appears to have a reddish tint. Up to 1964 seems to be one class, and then there are classes by date features and numbers after that. I am not trying to determine a value here, just establish a date for what I have. I know I bought it in the 60's, and I would have been 15 in 1964, so it is very possible it is from that class or group of knives indicated as something like 1940 to 1964. How do I figure this out?