Sterling Silver and copper both tarnish over time. 100% silver is too delicate for jewelry; sterling silver is made of 92.5% silver and is generally alloyed with 7.5% copper to make it sturdier, while maintaining its elegant and classy appearance. I recommend a polishing cloth (my favorite are Sunshine Cloths, which will work on both copper and silver) to get your pieces shiny if they have developed a layer of tarnish. Tarnish is the result of oxidation. I purposely oxidize (also called antique) the engraving in some of my jewelry, so it is best not to use any sort of liquid or paste polish. If your piece has collected dirt and lint over time, you can use warm water, mild soap, and a soft toothbrush to clean out the nooks and crannies. I frequently use turquoise and some other semi-precious stones in my work. Turquoise is a fairly porous stone that rates a 5-6 on the Mohs hardness scale. This means that discoloration and surface damage can occur if not properly cared for. Turquoise is best cleaned using warm water and a soft cloth with no cleaning agents. Some tips to prevent oxidation and keep your pieces with turquoise and other semiprecious stones in good shape:

Store your pieces in an airtight container, away from sunlight and moisture.

Remove during exercise.

Remove during swimming or showering.

Remove while cleaning with chemicals.

Avoid direct contact with perfume and cosmetics.

Remove while sleeping.

The engraving on jewelry and tack pieces that get regular/everyday use will have a worn appearance over time due to the nature of sterling silver and the other metals I use in my work.The oxidation will slowly fade and the silver will get scuffed, scratched, and worn down. I personally really like the look of worn pieces. I do my best to build solid accessories that will last you many years, even with regular use. If you would like to prevent the natural look of worn pieces, it is best to follow the above advice and not wear your jewelry during everyday activities.