Herkimer Diamond: What is It, Where to Find It?

What is Herkimer Diamond?

Herkimer Diamonds are double-terminated quartz crystals that are found in and around Herkimer County, New York, USA. They are not true diamonds, but they are prized for their clarity and natural faceting. 

Herkimer Diamonds are typically 18-sided, with two pointed terminations. They can range in size from a few millimeters to several inches in diameter.

Herkimer Diamonds are thought to have formed over 500 million years ago, when the Mohawk Valley region was covered by a shallow sea. The quartz crystals formed in cavities in the seafloor, and were eventually buried by sediment. Over time, the sediment hardened into rock, and the quartz crystals were preserved.

Herkimer diamonds can be found in a variety of colors, including clear, white, brown, and black. They are typically small, ranging in size from a few millimeters to a few centimeters. However, some have been found that are over 10 centimeters in size.

These quartz crystals, which geologists theorize formed extremely slowly in small solution cavities or vugs, have 18 facets (6 sides) and two terminations. There are also larger cavities that are several feet in diameter that are called "pockets". Herkimer diamonds are found clear, cloudy, smoky or even containing a variety of rare impurities. Impurities (rare and general) can include clusters, scepters, fluid inclusions (sometimes incorrectly called enhydros), phantom, and bridge crystals.

Herkimer Diamond
Herkimer Diamond


A fluid inclusion is a pocket within a crystal containing liquid, usually water, sometimes also methane or oil, and rarely, smaller crystals. A phantom is a crystal containing other visible crystals of the same type, a skeletal crystal contains a series of crystal edge outlines inside the crystal and a hopper crystal has its faces replaced by a step like pattern.


What is Herkimer Diamond,
Herkimer Diamond. Photo: Northern Maine Minerals

Where to find Herkimer Diamond?

Herkimer diamonds are a popular tourist attraction in upstate New York. There are several commercial mines where visitors can dig for their own diamonds. Herkimer diamonds are also available from many rock and gem shops around the world.

Herkimer Diamond Mine, Herkimer county, New York

The undisputed king of New York gem digging, this iconic location is famous for its "diamonds" (double-terminated quartz crystals). They offer public and private digging areas, with beginner-friendly instruction, guided tours, and even educational exhibits.

Their website provides detailed information, pricing, and even a virtual tour: Herkimer Diamond Mines

Address: 4626 State Route 28 North Herkimer, NY 13350

Grove Diamond Mine, St. Johnsville, New York

Crystal Grove Diamond Mine is the place to go to find Herkimer diamonds, beautiful quartz crystals that are fun to mine. These crystals were first discovered in New York, and the perfect clarity of some of these stones makes them very popular with gem hunters.

Crystal Grove boasts a relaxed atmosphere and family-friendly amenities. They offer public and private digging areas, along with on-site camping facilities.

Fees: Adults (13 and up) pay $15 to mine, kids (6-12) pay $10, and kids under 5 are free. Camping fees are $30 per night for tent sites, $40 per night for RV sites with water and electric, and $50 per night for RV sites with full hookups. The mine is open from 9am to 5pm, seven days a week.

Address: 161 County Highway 114 Saint Johnsville NY 13452
Herkimer Diamonds
What is Herkimer Diamond, Where to Find Herkimer Diamond?
Herkimer Diamond Quartz Cluster from Ace of Diamonds in New York
Credit: The Crystal Collector

The Old Forge Gem Mine in Old Forge, New York

Old Forge Gem Mine is a gemstone mining operation located in Old Forge, New York. It is a family-owned and operated business that has been in operation since 1963. The mine offers a variety of gemstones to mine, including garnets, amethysts, tourmalines, and smoky quartz. The mine is open year-round, but the best time to visit is during the summer months when the weather is warm and sunny. There is a small fee to enter the mine, and all equipment is provided. Visitors are allowed to keep any gemstones that they find.

Additional information about the Old Forge Gem Mine:

  • It is located at 2888 State Route 28, Old Forge, NY 13420.
  • The phone number is (315) 369-4451.
  • The hours of operation are 9am to 5pm, seven days a week.
  • The admission fee is $10 for adults, $8 for seniors, and $5 for children ages 6-12. Children under 5 are free.
What is Herkimer Diamond, Where to Find Herkimer Diamond?
What is Herkimer Diamond, Where to Find Herkimer Diamond?
© Rainbow Doorways.

Tips for finding Herkimer Diamonds

  • Go during the spring or fall, when the weather is cooler and less humid.
  • Look for rocks with small, dark holes. These holes are called "vugs," and they are most likely to contain Herkimer diamonds.
  • Use a hammer and chisel to break open the rocks.
  • Be patient! It can take some time to find Herkimer diamonds.
Aesthetic Herkimer Diamond Matrix specimen found recently at the “Ace of Diamonds Mine” in Middleville NY
Aesthetic Herkimer Diamond Matrix specimen found at the “Ace of Diamonds Mine” in Middleville NY. Photo: Frank J McGivern Jr

See also:
6 Places Where Can You Go to Dig for Gemstones in California
What Is Geyser Opal, and Where You Can Find It?
Dig Your Own Unique Opals From Nevada
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