crystal stone

crystal stone (plural crystal stones)

1. (now historical) Crystal; a piece of crystal.
   • 1590, Edmund Spenser, “Book III, Canto I”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie, →OCLC:

     A goodly Lady did foreby them rush, / Whose face did seeme as cleare as Christall stone [...].

   • 1665, John Bunyan, The Holy City:

     All which words, with the nature of their light and colour, the Holy Ghost doth in the vision of John comprise, and placeth within the colour of the jasper and the crystal-stone.