Photos of Members' Collections

These are cuprite from Onganja, Namibia, cut recently by Duncan Miller. The rough was acquired in 1975 from Sid Pieters in Windhoek. The round stone is a 29.16 ct, 16 mm diameter nine-mains brilliant. The 14.38 ct, 16 mm long pear-shaped stone is based on ‘Allan’s Challenge’ by Arya Akhavan, with a simplified pavilion. The 4.78 ct, 8 mm triangular stone is Tom Herbst’s ‘Tris de Garnet’. The square stone is a 34.32 ct, 15.5 mm wide step-cut crown on a simple brilliant pavilion from Jeff R. Graham’s ‘Quick Cushion’. All the stones except the Tris de Garnet have shallow pavilions to reduce absorption of the reflected light. They were cut on a 1200 mesh sintered bronze/diamond lap, pre-polished with 8000 mesh diamond on a Batt lap, and polished with 100 000 mesh or 200 000 mesh diamond on Gearloose’s Lightside laps, which are meant to replace wax laps. With a Mohs’s hardness of 3½–4 and a metallic lustre that shows up the faintest scratch, cuprite is difficult to polish. Duncan says he is still working on getting a better polish!