Stylish 1970s Retro Tourmaline & Diamond Set Ring 3.1 grams size N.

This is an unusual ring set with 4 large oval tourmaline stones which are a slightly brighter green than my pictures show and a bright little brilliant cut diamond at its centre. 3.1 grams is the weight and it is size N. Great condition although its makers and hallmarks are rubbed and not possible to read. Tests as at least 9ct Gold, thanks for looking.