What a lovely cameo beauty! Since the late 19th century, the shell species most used in good quality cameos has been Cypraecassis rufa, the BULLMOUTH HELMET. This shell has white and dark brown layers and is also known as sardonyx shell, because it looks similar to the layered agate known as sardonyx.
The finest hand-carving of these particular shells takes place in Italy. The world CENTER for cameo carving in shell is Torre del Greco, in Italy.
The approximate date can be determined by the format of the Italian hallmark. Star, followed by Assigned Number for Jeweler, followed by Province Abbreviation began in 1968. Your cameo is therefore not an Antique Cameo and made sometime between 1968 to the Present.