North by Northwest 
  by Tom Herbst
      North by Northwest is a very simple design.
        It displays the best properties of both a classic "sparkly" stone and
        a more geometric reflector. It  works well in medium index material such
        as tourmaline and beryl. 
      The name comes from the resemblance of the crown and pavilion facets
        to a compass "rose," the direction indicator  on old-styled maps. The
        pavilion points North, and
        the crown
        points Northwest, hence the cinematic name. 
      North by Northwest is a straightforward design suitable for all skill
        levels. BOG-optimized for ISO (94%) and tilt in Tourmaline. For beryl,
        tangent ratio the pavilion from 43.2° to 44.2° and the crown
        from 32.2° to 40°. 
      Pictured below is a matched pair (more or less) of  6 mm, 1
          carat stones cut in flawless, pale, green-blue tourmaline
          (left) and synthetic emerald (right).  |