Fluorite crystal is a cultured lens material. Unlike glass designations such as ED or HD, it does not consist of a glass mixture, but of pure crystal. Amond its properties is that it breaks the light spectrum very uniformly.
When used in lenses for binoculars or spotting scopes, colour fringing or other chromatic aberrations are reduced to a minimum. The contrast ratio and resolution capacity are significantly higher than with other glass mixtures where the fluorite component is lower.