Chalcedony. One of the stones described as forming the foundation of the new Jerusalem. Revelation 21:19. Chalcedony is ordinarily understood to be a species of agate, milky white or pale yellow, often with a wavy internal structure. Some liken it in color and want of transparency to skimmed milk. Another description represents it as of the color of a pale flame, shining out of doors, obscure in a house, not easily cut, and attributes to it the tower of attracting light substances. Also it has been supposed to be turquoise, carbuncle, or ruby, or an inferior kind of emerald.