Help identifying marking on necklace-fS

[ddsavaj]

Hi thank you for your time in looking at this!

I have searched for months to try to find what this mark means. This was bought at an estate sale, so I have no additional details. I know what 925 means, I just need to figure out if the fS in a circle is a makers mark and I’m hoping someone knows! Please see photos. Thanks in advance!

[ddsavaj]

I have finally found the maker. Franz Scheurle!

Here is the link to the updated website, please edit or delete if not allowed.
http://www.silvercollection.it/GERMANMAKERSF.html