Italian, late 18th century.
Ring size P UK / 7.5 US.
The intaglio measures 2 x 1.8cm.
There is a stable internal fissure within the intaglio.
For a similar example see ‘La Collezione Paoletti, Stampi in vetro per impronte de intagli e cammei, Tomo I, cassetto 9, fig. 574’.