Suisse Mark Silver Necklace - Vintage? Fine jewelry vs. Costume?

After Mom passed in March of this year, I inherited all of hers and her Mother's jewelry. There is a bit of fine jewelry, albeit, inexpensive fine jewelry but more fascinating is the large amount of costume jewelry. 90% of the costume jewelry belonged to my Grandmother.

She was born in early 1900's, so any amount of jewelry that would have likely been accumulated from 30's to 70's (late). She died in early 80's. She seemed to LOVE brooches, Canadian Maple leaves, etc.

This necklace was entwined with a lot of my Grandmother's jewelry. I'm not sure how to properly 'classify' this one. Based on the writing on the 'pendant' part of the necklace, I take it the necklace is silver.

The verbiage on the pin is "CREDIT SUISSE" "59 FINE SILVER 9990" Then possibly a mark along with wording or the whole part is the mark/maker info - there is a circle with what looks like "CHI" and then "ISSA EUR JONDEUR".? Maybe 'FONDEUR" Back has "CREDIT SUISSE" marked over and over in a diagonal pattern

I'll try to class it correctly and do my google searching but figured someone here may recognize it instantly...I did find an image that matched perfectly. It described it as "Vintage Silver Credit Suisse Bar In Gold Frame Pendant / Charm" I'm unsure if the chain that it is on was purchased separately - looks like it may have been. I do think the silver is framed with gold, exactly like the one I found. Still unsure of time period these would have been issued based on the marks.