The base plate (the silver part) arrived discolored. It looks as if the base plate was made of brass and the silver plating has somehow dissolved.
This is not the case, of course, this is the only way I know to accurately describe what it looks like.
I need some recommendations on how to clean the base plate of these stains.
When I received this block, it was vacuum sealed in its original package and I have no idea how it came to look like it does.
I can't post a picture as I have no camera or any device that has a camera built into it. I've lived over 56 years without a camera and have no intention of buying one now.
I've never owned anything made of silver other than coins from the US, British and Australian Mints. They're of even more pure quality silver than this waterblock so I really don't know what happened for this block to be stained as it is.
I bought this block brand new almost six months ago and have just finished buying all of the parts to build my new computer.
I thought that the block had a sticky type of plastic on the base plate, as most new blocks, and that was why the block looks as it does. I wish I had gone ahead and opened the vacuum package and checked, but I thought it would be better to leave it sealed until I could use it.
I did a Google search on cleaning silver, but they all said to use table salt plus baking soda and to boil the silver in water with a piece of aluminum foil. I don't want any salt in contact with any of my computer parts.
Thanks for any help.

Thanks for the reply!
As I said, the only way I knew to describe exactly what this looks like, is as if it were just plated. It's a real block of silver. I have no doubt about that.
I'll check around locally and find some metal polish to try. I was worried that polish may leave behind some kind of residue that might react with the Arctic Cooling MX-2 I'll be using.
Thanks again.