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I’m familiar with this type of jewelry and it’s putative makers, which in retail stores are often made up names with phony NA bios created by the Importers and distributors of the merchandise. Chickfarmer is correct about origin. Items of this type are often made offshore, imported and then merged into commerce along side items legitimately made in the US. Although country of origin labels are required for import, these labels tend to disappear quickly once items reach our shores.
Markups are often 10 times or more the original import price of the merchandise, so assigning value is nearly impossible.