All Jewelry from Hildur Hafstein is made of .925 sterling silver and many pieces have surface treatment like gold plating or are oxidized.
These surface treatments will fade over time because of contact with clothes, hard surfaces, sweat, perfume, hairspray, air pollution to name but a few. Everyday or very frequent use, may speed up this process, especially on items like rings and bracelets, which have more frequent contact with skin and surfaces.
When you're not wearing your jewelry you should store it away, preferably in a jewelry box in a dry place like your bedroom. Exposure to moisture and abrasive cosmetic products in your bathroom will speed up tarnishing and oxidation.
You should remove your jewelry when working out in the Gym or when you go to the swimming pool, Jacuzzi, sauna/steam room or while bathing or showering as it can cause breaking, tarnishing and damage. Gently wipe your jewelry clean with a soft cloth after each wear to remove make up and oils and stove them away.
Remember: You should treat your jewelry with care and like for example watches it may need maintenance from time to time, cleaning, additional coating or fixing clasps. 
If you have a question about repairs, please contact us at info (at) hildurhafstein.com