Definition of Cameo is a method of carving a relief on gem stone, contrast with Intaglio that is carved into a gem stone, negative that was in antient times, used as a stamp.
Your brooch is made in metal, therefore, it cannot be called cameo. It's a loose wax casting. The marking indicates who was the original maker for this model that was reproduced in thousands.
Cheers. Alec Stromberg www.strpmbergtime.com Los Angeles, California
