Coloring acquired from the bag while a coin was stored. Cloth coin bags contained sulfur and other metal-reactive chemicals. When stored in bags for extended periods, coins in close proximity to the cloth often acquire beautiful red, yellow, blue and other vibrant colors. Sometimes the weave of the cloth is visible in the toning. Some coins have crescent-shaped toning because another coin was covering part of the surface, thus preventing toning. Bag toning is seen most often on Morgan silver dollars.

Anyone see this yet? 

Not to take away from Brock Osweiler's performance; the guy straight up owned the Patriots in the fourth quarter. But the choice by SI to choose a photo with a potential (i.e. probable) missed call in the background is curious. 

Fresh coins going out for grading. We'll list 'em when they come back!

Polyvinyl Chloride is a somewhat active chemical found in some types of plastic coin flips. PVC will cause some coins to tone or turn green over time. The effect is often removable from silver coins, but PVC has been known to wreak havoc on copper, and to a lesser extent nickel coins, especially if the coins have been stored in warm or damp places over long periods of time.

Non-circulating legal tender. These coins are issued in "limited editions" for collectors, and sold for far more than their face value. While these coins are technically legal tender, their bullion value usually far exceeds their face value.