WHY DOES SILVER TURN COLORS AND WHAT COLORS DOES IT TURN?
First of all Sterling Silver is made from 92.5% PURE SILVER and 7.5% other stuff, usually copper. But it will tarnish. Why?
As sterling silver comes into contact with Oxygen and Hydrogen Sulfide which is present in the air around us, a chemical reaction occurs. (unavoidable LOL) This is called oxidation. NOTE: Oxidation is a primary sign that silver is in fact, Sterling Silver.
Over time, the silver starts to turn yellow and can even look like gold, but it gets darker and darker and blacker and blacker as time goes on. Then it looks like the first picture above.
Then there are the perfumes we wear. These can mess with silver jewelry. We always say put the perfume on, wait till it soaks in, THEN put on the necklace. Same thing with various lotions etc.
In fact mostly what keeps a necklace tarnish-free is our skin oil which coats it if you wear it 24/7. However, even that is not guaranteed. All of us have different levels of pH in our bodies, some more acid or more alkaline. I do not know which (acid or alkaline) reacts badly to silver but one of them does and if that is the case, you get tarnishing so bad it actually rubs off on you in black. You who have this issue know who you are. (solution - white gold)
Most Jewelry Stores have the factories PLATE their silver jewelry with some sort of anti-tarnish plating. From plastic-like substances to Rhodium and Nickel, these then avoid tarnishing.
We do not like Rhodium plating because it then does not look like silver anymore and as to Nickel, so many people are severely allergic to it, it is not even used anymore.
For the "plastic" types of anti-tarnish, they tend to wear off unevenly and you get a blotchy piece of silver, and in that case, we DO recommend just throwing it away.