All of my pieces are one of a kind, handmade items and most of them have patina applied during the finishing process. I do not use any chemical sealants and this patina may wear off over time when in contact with your skin.
Sterling silver will tarnish over time, this is a natural occurrence. While I do not recommend any silver polishing compounds or cleaning solutions, you may use the silver polishing cloth to remove tarnish (it also diminishes with wear/skin contact, just like patina). Use light touch and keep in mind that silver is a soft metal and will wear down some each time you polish.
Do not polish stones with a polishing cloth, they may become dull looking.
Always remove your jewelry before gym/water activities, bathing, cleaning, sleeping, lotion applying, etc.
Finally, much like us, jewelry goes through stages. What was once new and polished, over time becomes older and get battle scars. Enjoy it and savor the memories!