cameo earrings with different silhouettes

I have a pair of old hand carved cameo earings with a twisted chain spiral borders. They have a brown back with a white woman's face. The cameo is carved out of one peice of material and both are different and not perfect face silhouettes.

B.5.80C or 8.S.80C is marked on the bottom of both earrings.

What does this mean and estimate of value?