Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/111

 tal plate of cast iron, fourteen or fifteen inches in diameter, (called a skive,) fixed on aspindle, and capable of being put into rapid motion by means of a larger wheel, five or six feet in diameter, and turned by an assistant. In order to -keep the Diamond perfectly steady while the polishing: of each facet is going on, the following contrivance is had recourse to. .A copper cup (called a dopp,) about three quarters of an inch in depth and the same in width, and furnished with a stem about four inches long, of stout copper wire, is filled with plumber's solder, which projects in a conical form beyond the rim of the cup: in the apex of this cone, the solder being softened by heat, the diamond is imbedded with the facets to be po-