Herkimer Diamonds are quartz crystals prized for their unique formation and sparkling appearance. Primarily found in Herkimer County, New York, they get their name from this location. Their naturally faceted, double-terminated shape and exceptional clarity led to their popular “diamond” moniker.
Understanding Herkimer Diamonds
Herkimer Diamonds are quartz crystals that began forming approximately 500 million years ago within cavities of dolostone. This geological process involved ancient shallow seas depositing sediments that later lithified into bedrock. Acidic waters then created voids where silica-rich water deposited quartz crystals over time.
These crystals developed their double-terminated structure, meaning they have naturally occurring points at both ends, unlike most quartz crystals. Their slow growth within these enclosed pockets resulted in exceptional clarity and often 18 natural facets. This natural faceting gives them a polished look without human intervention.
Herkimer Diamonds Compared to True Diamonds
Herkimer Diamonds differ significantly from true diamonds in several fundamental ways. Chemically, Herkimer Diamonds are composed of silicon dioxide, classifying them as quartz, while true diamonds are made of pure carbon. This compositional difference impacts their physical properties.
On the Mohs hardness scale, Herkimer Diamonds rank between 7 and 7.5. In contrast, true diamonds are the hardest known natural substance, scoring a perfect 10 on the Mohs scale. The Mohs scale is not linear, so a diamond is considerably harder than quartz.
Herkimer Diamonds also form under different geological conditions, crystallizing near the Earth’s surface within sedimentary rock cavities. True diamonds, however, form deep within the Earth’s mantle under immense pressure and heat. Despite their visual resemblance, Herkimer Diamonds are a distinct mineral and are not considered “real” diamonds in the gemological sense.
What Determines a Herkimer Diamond’s Worth
Several characteristics influence a Herkimer Diamond’s worth, primarily as a mineral specimen rather than a precious gemstone. Clarity is a significant factor, with clear crystals being the most sought after. Crystals with cloudiness or numerous internal fractures have a lower value.
Size also plays a role, as larger, well-formed crystals command higher prices. The perfection of its double terminations is another important aspect, with fully intact and undamaged points being highly prized. Crystals with irregular shapes or fewer points are less valuable.
Some inclusions can enhance a Herkimer Diamond’s value, such as internal moving air or petroleum bubbles, known as enhydros. Black hydrocarbon inclusions, also called anthraxolite, or rare phantom crystals can increase their appeal. The overall aesthetic appeal and unique formations, including clusters of crystals, contribute to their desirability.
Collecting and Commercial Value
The commercial value of Herkimer Diamonds is modest when compared to true diamonds. Their abundance as a quartz variety contributes to this difference in pricing. Individual specimens can range widely in price, from $0.10 to $14 per carat. Large, high-grade specimens might sell for $300 to $1500, while smaller ones can be as inexpensive as $5.
Herkimer Diamonds are primarily collected as mineral specimens due to their unique natural beauty. They are also popular for use in jewelry, often in their raw, uncut form, and have gained attention for metaphysical purposes. These crystals are commonly sold online, at gem and mineral shows, and directly from mines in Herkimer County, New York, where visitors can even dig for their own specimens. Their appeal lies in their distinct natural formation and collectibility rather than as a traditional investment gemstone.