Even jewelry you pay more for can have the same effect~ because the expensive metals aren’t completely pure- regardless of cost. Platinum is one metal that usually doesn’t react with skin so no worries if you buy platinum jewelry.
To try to stop gold jewelry from reacting to your skin make sure that you don’t have made from cheap metal and then plated – its a cheaper metal with a thin gold layer that will wear off. For ‘real’ gold jewelry choosing a higher karat will lower your chances of green skin. Jewelry made from copper will react with skin and theres really nothing to be done.

Stay away from wearing jewelry when you’re sweating a lot because that can speed up the reaction between your skin and the metal you might also ask your jeweler if they can add a layer of protective coating – in order to try to stop the reaction or minimize it. If you do this you can keep wearing your base metal jewelry without worry.
Don’t forget; your skin turning green is a harmless reaction. It’s just a skin reaction and not allergies.
Allergies (such as those to nickel) causes reddening plus it could also make your skin feel itchy and inflamed. Which is a far cry from the green skin that you see from jewelry.
If you do show signs of allery stop wearing the jewelry. Green skin shouldnt scare you ore keep you from wearing your favorite pieces just be sure to keep the skin clean so it doesn’t look bad.

At the end of the day coating it is usually the best option.