The most spectacular toned dollars result from decades of storage within a canvas mint bag. Only coins stored in canvas bags develop a true rainbow pattern, so collectors and dealers often misattribute rainbows to other toning sources. Coins touching the side of a bag react with trace elements of sulfur remaining in the canvas from the bag's manufacturing process. This chemical reaction causes the toning. Coins remaining motionless for at least fifty years tarnish predictably according to their position in the bag. Have a great time looking at the mint bag toned coins, and give us a call if you see any items of interest. Please order using the appropriate inventory number next to each coin. Enjoy! View Coins for Sale