Small Silver Pendant with a Blue Stone (Glass?) and Pearl

This is a small silver pendant from my collection, also an inherited piece. It is quite small, less than an inch all together. It is marked STER on the back. I do not know if that is a stone or glass, I am assuming it is glass. I think also early 20th century. The pearl must be a natural pearl? Any thoughts appreciated.

 

I will take a gander that the stone is glass, pearl is real. My take on first look is an art nouveau era lavalier pendent missing its bail. While not a high end piece, it is a pretty tid bit none the less

The History & Beauty of the Lavalier (marketsquarejewelers.com)

 

Thanks! Learned something new once again!