Quick Facts
Formation & Origin
Herkimer diamonds are not diamonds - they're doubly terminated quartz crystals (naturally pointed at both ends) found in dolomite rock in Herkimer County, New York. Their exceptional clarity and natural double termination make them look like faceted gems straight out of the ground, which earned them the 'diamond' trade name.
These crystals grew approximately 500 million years ago (Cambrian period) in cavities within dolostone - a magnesium-rich sedimentary rock. Unlike most quartz crystals, which grow attached to matrix with a single termination, Herkimer diamonds formed freely suspended in fluid-filled pockets, allowing them to develop terminations at both ends. The cavities also limited their growth, keeping most crystals small and concentrating their clarity.
The most prized specimens are water-clear with brilliant vitreous luster. Some contain black carbon inclusions (called 'smoky' or 'carbon Herkimers') or fluid-filled enhydro cavities visible inside the crystal. Mining is done by hand in specific quarries and road cuts in Herkimer County - you can visit and mine your own.
Identification Guide
Herkimer diamonds are identified by their exceptional clarity, double termination (points at both ends), and brilliant vitreous luster. At hardness 7, they're standard quartz. The crystals are typically small (most under 2 cm) and remarkably clean.
Distinguish from doubly terminated quartz from other localities (marketed as 'Pakistan diamonds,' 'Tibet diamonds,' etc. - these are NOT Herkimer diamonds regardless of appearance), from actual diamond (much harder at 10, different luster), and from cut glass (no natural crystal faces, may have bubbles). True Herkimer diamonds come only from Herkimer County, NY.
Spotting Fakes
The main issue isn't fakes but mislabeling. Doubly terminated quartz from Pakistan, China, Afghanistan, and Mexico is frequently sold as 'Herkimer diamond' or 'Herkimer-like.' True Herkimers come only from Herkimer County, New York - the name is geographic, not descriptive. Other doubly terminated quartz may be beautiful but isn't Herkimer diamond. For guaranteed provenance, buy from Herkimer County dealers or mine your own at the tourist quarries.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
Herkimer diamonds are considered among the most powerful quartz crystals in the crystal healing community. Their exceptional clarity and double termination are interpreted as representing perfect energy flow - receiving at one point and transmitting at the other. Practitioners use them for attunement, dream work, and amplifying the energy of other stones. The Mohawk people of the region have traditional connections to these crystals. The ability to mine your own adds a personal connection valued by practitioners.
Where It's Found
The only source of true Herkimer diamonds
Price Guide
Good to Know
Scratch test: At hardness 7, Herkimer Diamond can scratch glass and steel. It's durable enough for any type of jewelry.
Sources: Found at only one location on Earth - United States. Supply is inherently limited.
Heft test: Herkimer Diamond has average mineral density (2.65). It feels about as heavy as you'd expect from a stone its size.