Diamond Quartz

Diamond Quartz is the collector's trade name for naturally doubly terminated crystals of quartz (SiO2), prized for their exceptional clarity, sharp geometry, and diamond-like brilliance despite being chemically ordinary quartz with a hardness of 7. The type locality and still the most famous source is Herkimer County, New York, where crystals grow free-floating in solution cavities within the Cambrian-age Little Falls Dolostone along the Mohawk Valley. Because contact with the host rock is minimal, these crystals develop terminations on both ends, an average of 18 facets, and a distinctive pseudo-octahedral outline. Within this same district, material is also traded under the older regional names Little Falls Diamond and Middleville Diamond, and historically the crystals were gathered and traded by the Mohawk people long before commercial mining began.

Beyond New York, visually identical doubly terminated quartz occurs at a handful of celebrated deposits worldwide, each with its own local nickname. In Arizona, the Diamond Point locality in the Mazatzal Mountains, Gila County, produces crystals marketed as Payson Diamonds, occasionally showing a faint amethyst tint on their terminations. Similar material comes from vein and cavity deposits in Afghanistan and Pakistan, the latter well known for gem-clear specimens containing moving water bubbles, or enhydro inclusions. Additional occurrences are documented in Norway, Ukraine, China, and parts of Tibet, though none carry the same market recognition as the Herkimer originals. Inclusions add further collector interest across all these sources: black particles of anthraxolite (hydrocarbon), trapped petroleum, carbon dioxide bubbles, and associated minerals such as dolomite, calcite, pyrite, and sphalerite frequently accompany the quartz and can dramatically increase a specimen's rarity and value.

Collectors seek Diamond Quartz precisely because double termination is uncommon in nature, a result of crystals growing suspended within open vugs rather than anchored to matrix. Water-clear, inclusion-free crystals from Herkimer County remain the benchmark for the variety, while amethystine Payson Diamonds, hydrocarbon-included Herkimers, and enhydro-bearing Pakistani crystals each offer distinct, locality-specific appeal for thumbnail and miniature collections, jewelry cutting, and display pieces alike.