Those photos are of the Obverse (Front) of the coin. The back is known as the Reverse. It just looks like staining if you are referring to the colour. In the future, please post photos of both sides of the coin.
Odd staining like this is often environmental damage - the coin may have been sitting in a chlorinated pool, or on an uneven surface in the open air, for some time, and the chemicals from the surrounding environment affected parts of the coin and not others.
In the end, it's "just odd staining", which can be recreated easily using chemicals (I could make coins that look more or less the same as these in the lab where I work, using just dilute acid and a paintbrush), and is not of much interest to collectors.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis