Amazon does not state they support a specific independent third-party audit scheme. "If we became aware that a supplier was sourcing gold, tin, tungsten, or tantalum from the DRC region, we then reviewed the smelters or refiners identified by the supplier against lists of certified conflict-free facilities in order to determine whether the smelter or refiner that processed those minerals had been audited and certified as conflict-free by a reputable independent third party."