About the materials
Bronze and sterling silver naturally develop a darker patina as they react to the environment. Including but not limited to: wearer's skin (your personal chemistry), water (chlorinated and saltwater), along with, oils, lotions, perfumes, etc.
If you would like to brighten up your jewelry use a polishing clothe, this will remove some of the patina on the surface of the metal.
Please contact me here if your have any questions: firstname.lastname@example.org