Herkimer diamonds are unique double-terminated quartz crystals found primarily in Herkimer County, New York. They are known for their clarity and natural faceting, which gives them a diamond-like appearance. These crystals typically form in limestone and are often found in clusters, making them popular among collectors and jewelry makers. Despite their name, Herkimer diamonds are not true diamonds; they are a type of quartz. Their distinctive features include a high degree of transparency and a natural brilliance that can resemble that of real diamonds. Many people appreciate them for their beauty and metaphysical properties.