Stipple engraving is done entirely by hand; there is no machinery involved.  A very hard, very sharp point, either diamond or tungsten carbide, is tapped onto the surface of a crystal glass.  The tiny dots that are produced are used to make up the design.  The closer together the dots are, the whiter the surface. Varying the density of the dots produces a range of tones, from the black of the untouched glass to the white of the closely engraved area; a picture is formed using the light that has been trapped in the glass where the surface has been punctured. The resultant engraving has a delicate, ethereal quality that cannot be produced by any other method of engraving. To be seen at its best, stipple engraving needs to be properly lit.