A metrology system comprises a support structure, a fixture having a bottom surface resting on a surface of the support structure and moveable relative to the support structure, and a first measurement assembly for interacting with a workpiece held by the fixture to measure a characteristic of the workpiece. One of the bottom surface of the fixture and the surface of the support structure comprises sapphire, and the other of the bottom surface of the fixture and the surface of the support structure comprises a metal.