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.