William Chaloner's Groat

Origins
William Chaloner was a coin counterfeiter and con who was imprisoned several times in Newgate Prison, finally convicted by Isaac Newton and hung at the gallows. He also posed as a quack doctor, soothsayer and faked lottery tickets. One of the first coins he counterfeited was the groat, being a quick learner and becoming skilled in making them.

Effects
When the coin is held in one hand and another object in the other, that object turns into money that is legitimate and in circulation. The issue is that the any person who uses the groat wants to take riskier and riskier ventures.