Metallic waxes are most commonly available in "metal colors" such as gold, silver, or copper. However, some brands also carry other metallic (and non-metallic) colors of waxes. The consistency of the wax varies from brand to brand.
These products can be applied to raw or cured clay, but are most commonly applied after curing. You can completely cover a piece, work it into the crevices and wipe away the excess to antique the piece, or highlight only the uppermost parts of the design.
Apply most metallic waxes by rubbing a bit onto the clay, letting it dry thoroughly, and buffing to a high sheen. If the piece will be getting much wear, it is best to seal it after buffing. It is especially important to seal an item that will be worn against skin or clothing, as this prevents the wax from rubbing off and leaving stains. Sealing can also prevent tarnishing, which may be a problem with some metallic waxes and pastes.