Can anyone help me date this Cameo necklace and maybe identify the dark yellow stones?

by Debra
(Norfolk, VA)

Antique Cameo Necklace

This cameo necklace belonged to my great-grandmother, she lived in Canada and Maine 1890-1981. It appears to be Silver with amber stones. The cameo is maybe carved sardonyx? I don;'t collect jewelry at all but want to take good care of it if it's valuable.Any ideas?