what an interesting pendant. It looks like it could be a studio jeweller whose crafted this pendant; the mark may not even be registered. As it's clearly marked on the reverse "925" which is a silver purity mark it will not be the "OS" initial of maker Ontario Silver Co. (on Silverplate, Niagara Falls, NY, USA, & Ontario, Canada) - ca 1883 - 1915.
You might like to check in the Jewelry Resources under US Jewelry Marks 1922.
Thanks for writing in... Happy Hunting! Yvonne Hammouda-Eyre Stay up to date with all the latest Antique, Premier and Pearl Jewelry News, and subscribe to our newsletter....