Herkimer Diamond Quartz Crystal Most Crystals have Contact Marks from the Matrix where they grew & Inclusions from gases and minerals within. These are common, anything with serious damage or a Contact Break where a face was attached to matrix is noted and shown in Photos below. The A / A+ / AA grade Crystals are the best of the best. Less than 5% of all the Crystals mined fall into this category. See below for more info. Location : Middleville, NY (Herkimer Diamond Mines) Gem Crystals (A, A+ or AA grade) over 1/2" (12.5mm) are very rare, These are mostly Floater Crystals, meaning there are no contact marks from the matrix. These crystals become even rarer at 1" in size with good clarity, 2"+ clear is rarely seen, especially in single crystals with no contacts or attached crystals. (Other Minerals, Hard Rock, Crystals, Quartz Crystal, Diamond Quartz, Herkimer Diamond, Quartz, Diamond Mines, Gems