How to tell a fake Morgan Dollar "Junk Silver" with the "Cartwheel Effect"

Ebay is a great place to buy Morgan Dollars. But how do you know if what you bought is the real deal or not? One way to check is to look out for the 'Cartwheel Effect' as highlighted in the video below:

What is the cartwheel effect?

The cartwheel effect is a term that describes the rotating, windmill like effect of light that mint state coins exhibit. The cartwheel effect is best known for appearing on Morgan Dollars, due to a fortuitous confluence of coin design, planchet size, and die preparation methods, although the effect can be seen on nearly any mint state coin. The cartwheel effect is caused by flow lines that occur during the coin striking process, and the effect is somewhat fragile, disappearing as a result of circulation or the coin being cleaned.