Quartz and Diamond Ring. In the 1950s and 60s, a new genre of ring shot to popularity - the cocktail ring. These were larger jewels than the preceding periods had dared to imagine, and were designed to be worn on special occasions, with the right outfit, to spark conversation and stand out in the crowd. This ring certainly fits the bill, with an amazing octagonal mint-green quartz at its centre. Quartz in this rare colour is known as prasiolite, and is prized for its distinctive hue. Within a double halo of brilliant-cut and baguette diamonds, this extraordinary ring would be a great accessory for summer cocktail parties - best accompanied by a mojito in hand!