A citrine and aquamarine ring, by Bucherer, and an aquamarine and diamond ring

A citrine and aquamarine ring, by Bucherer, and an aquamarine and diamond ring
The cushion-shaped citrine collet-set to a calibré-cut aquamarine surround, finger size K; the oval-cut aquamarine collet-set within a brilliant-cut diamond-set broad band, finger size P
One ring with maker's mark CB (2)