1. Refining: If the nickel content in gold is too high, it can be sent to a professional refinery for refining to remove nickel and restore the purity of gold.

2. Polishing: If the surface of gold jewelry loses its luster due to the oxidation of nickel, it can be sent to a professional jewelry store for polishing to restore its original luster.

3. Replace jewelry: If the nickel content in gold jewelry is too high to be refined or polished again, consider replacing gold jewelry without nickel.