Abstract: Given the known position of the optical center of an unfinished lens which is to be contoured for an eyeglass frame, this invention relates to a single device for locating and aligning the contemplated geometric center of what will be the finished lens with the optical center so that a block may be secured to the lens at such geometric center for holding the lens for contouring. The device comprises a lens holder situated above a slidable grid scale which is used in combination with a fixed scale to decenter the lens on the lens holder such that the contemplated geometric center of the lens will line up above the position of a block that may be accurately moved into place by moving the same slider containing the grid.