Mexican Silver Monterrey Souvenir Spoon 1940s

How do I know its vintage provenance? My mother got it on a trip to Mexico just after she and my dad got married in the late 1940s. It's been in her jewelry drawer every since. But she's downsizing and doesn't mind my selling it here. In fact, she'd love a collector to have it! See pic for size with quarter for comparison. It's one of those little collector/souvenir spoons. The "Monterrey" is in a groovy Art Deco-style engraving. Sold as is, with tarnish and all. Offers welcomed. Make one if you want it! (dr)