Unfortunately, correct information can be very difficult to come by.
This only pertains the pre-Fender Korean-made guitars.
From about 1949 to 1957 watch for a white rectangular label that reads: The serial number will probably be printed in red, and the model number written in blue or black.
The label has a fairly ornate border around it, but the "Gretsch" is usually printed in a plain font.
Serial numbers have six numbers, with a three digit suffix. The final numbers are the sequential order of the model made during the lifespan of the model (not that year).
For example, 946119-976 would be a June 1994 Tennessee Rose, the 976th made.
This sticker, along with the "Made in Korea" sticker, went missing almost immediately — sometimes before the guitar even left the store.