Silver is valuable and beautiful to look at but because pure silver is soft and scratches it is matched with another durable alloy, copper to make Sterling Silver (92.5% silver+7.5% copper).
That's why it's stamped 925
The same is for silver plated jewellery.
The green finger/arm is a purely therefore a reaction to the copper alloy in the sterling silver especially if you have high body acidity. It happens to about 2~3% of people and percentage is increasing due to increased percentages of chemicals in our environment and food we eat.
•keep your jewellery clean When it's silver clean your jewellery every day
with a silver polishing cloth. When it's copper a lemon and salt mix. After about a week or two, the reaction will stop occurring or clean regularly
•some people apply a thin layer of clear nail polish on the inside of the ring which will prevent perspiration & sweat reaching the metal and reacting to it. I'm always wary of this as watch out for reactions to the alloys
•take all Silver off in the sea
•keep your skin dry when wearing jewellery.
Therefore don't always associate green with cheap jewellery
Also don't confuse patina (green effect) with allergy. I have a love of copper and the patina effect so I always carry wet wipes in the car incase I hadn't washed all green off in shower •ᵉᵗ.ͨ
l̤̮ol̤̮ The price we pay for vanity or for love of jewellery