Antique Victorian Hardstone 18k Cameo

Antique. Victorian agate hard stone cameo set in 18k gold. It can be worn as a brooch or a pendant.  I purchased this at a high end antique jewelry store in Chevy Chase.  It measures roughly 21/2 by 1/34”.  The setting has scrolling on the sides. Tested positive for 18k gold.  The back has sight marks to the gold. Beautiful piece. 
All sakes final so please ask questions.
Smoke free environment.