Seeking ID maker's mark earrings with SL and crown

[P-Dub]

I'm looking for help with an ID and approximate date for these button earrings. They were in grandma's jewelry box. That, the mark style and the oxidation (possibly from another piece in the box) tell me they are fairly old. I hope the photos show enough for someone to help. The mark is a crown with the "made in Mexico" text (in Spanish of course) underneath and "SL009250" above. I get that the 9250 is the silver quality, but can anyone tell me who SL is/was, who used a crown mark like this, what region it is from, or approximate date? I'm also interested in knowing more about this scratched-in design style. Thanks in advance.