There it is: a stamped or printed serial number.

"I need to know," the man said, his voice raspy. He placed the case on the counter and flipped the latches. Inside, nestled in faded blue velvet, was a Yamaha acoustic. It was beautiful, with a honey-burst finish that had mellowed into a deep, rich amber.

If you’ve just bought a used Yamaha FG800, stumbled across a vintage Pacifica, or inherited an old classical guitar from an uncle, the first thing you probably did was flip it over to look at the headstock.

: Usually found on a label inside the soundhole , stamped on the neck block (inside the body), or the back of the headstock.

The following resources are widely considered the most reliable for decoding: