A method of measuring spherically mounted retroreflector (SMR) with a 3D coordinate measurement device such as a laser tracker. The SMR includes an open-air cube comer retroreflector having a vertex point located near a sphere center of the SMR. Measurements of the SMR to the vertex point are corrected to indicate 3D coordinates of the SMR sphere center by accounting for SMR depth error and SMR runout error. The SMR is measured with the device from two stations having different reference frames. Transformation matrices between these frames are generated based on measurements of three retroreflectors, the SMR in a nest and the error vector of the SMR.