The largest use of rhodium, about 80% of the world’s production, is as a catalyst in three-way catalytic converters. A catalytic converter is a device fitted to vehicle to convert toxic exhaust emissions into safer substances. Rhodium is also used in the jewelry industry where it is often electroplated onto platinum or white gold to produce a reflective white surface in a process called rhodium flashing. It is also used as a coating for sterling silver to reduce the chance of tarnishing. Plated rhodium is sometimes used for optical instruments. It is also used in some alloys containing platinum and palladium for hardening and to provide increased corrosion resistance. A specialist device called a rhodium neutron detector is used to measure the neutron flux level in nuclear reactors. It can also be used as an electrical contact material.