Herkimer Diamond with A Black Pebble Ring$125 CAD Ring size approx. 6 ~ 6. 5 North American ring size Approx. pebble size 10mm x 7. 6mm & herkimer diamond size 8. 8mm x 5mm *Herkimer Diamonds are double terminated quartz crystal. They are known as one of the most powerful of all quartz crystals and often used in meditations. They act as powerful amplifiers when you are using them with other gemstones. Herkimer Diamonds clears chakras and purifies physical, mental and spiritual bodies.