Dating your gibson
Factory Order numbers with a letter from 1952 to 1961.
Exceptions: Some high-end models and lap steels from 1939-1940 have been added the letter A, to the prefixes D, E or F.
There should be a space after the 1st digit with the 4 and 5 digit serial numbers, and no space with the 6 digit numbers.
The 1st digit indicates the year of manufacture for the 4 & 5 digit serial numbers, these were used from 1989-1999.
But the serial number on a Gibson can tell you when the guitar was made.
With that information, you can determine its rarity and, ultimately, its worth. For acoustic instruments, the serial number is typically located inside the sound hole at the neck joint or on a piece of paper glued inside the guitar and visible through the sound hole.