Antique black enamel and Old Mine cut diamond three stone navette ring

Antique black enamel and Old Mine cut diamond three stone navette ring in 18kt yellow gold. Vertically set with three cushion shape Old Mine cut diamonds in grain settings, to a graduating three stone design, framed by a border of fine black enamel and further bordered by a incised edge, decorated with a pierced scalloped gallery and flanked by trumpeting shoulders which curves to a slim shank.