N.B. It is completely normal for copper, brass and zinc to change color naturally over time and lose their luster. Same thing for gold or rose gold plated stainless steel, avoid putting them under water, exposing them to body cream/oil or perfume so that they stay beautiful longer!
See an explanatory video on a method of cleaning copper and brass justHERE
Also, as the stones work energetically on your vibrational field, it is important to cleanse and charge your jewel so that its therapeutic properties are optimized.
How to do?
Just light a branch of Palo Santo or white sage and pass it several times over the smoke. Visualize it transporting negative energies out of the jewel and filling it with positive and benevolent energies.
Once charged, just before wearing it, hold the jewel in your hands for a few seconds and visualize its energy synchronizing with yours. Thereafter, program it by reciting this formula:
"I ask this jewel to assist me throughout the day in (desired property according to its file) for my well-being and that of all, so be it."
The more you do it, the more it will help you in this direction!
*Please note that crystals are intended to aid in your healing and are not intended to cure or treat any condition or are intended to replace any treatment plan set out by your doctor.