Abstract: A measuring apparatus for determining the location of a point in space using a coordinate measuring machine, such as a laser tracker. The apparatus comprises a retroreflector releasably coupled to a sphere of a tooling ball. The tooling ball is rigidly coupled to a mechanism whose position is to be found and whose movements can be monitored by repeatedly determining the position of the center point of the sphere of the tooling ball. The retroreflector is formed of solid glass and has a corner cube having a vertex which has a predetermined dimensional relationship with and represents the virtual location of the point in space, that is, the center point of the sphere. The retroreflector is configured to receive a beam of light from the laser tracker and then reflect and retroreflect the beam to the laser tracker to determine the location of the vertex of the corner cube and, thus, the center of the tooling ball.