They made round coins as a means of fighting coin clipping, which occurred back then, too. Interestingly, Isaac Newton invented modern coin ridges (reeding), to also help fight coin clippers, and made coin metal measurements even more precise, to combat counterfitters. He eventually became head of the British Royal Mint in the late 1600s.
https://www.ancientpages.com/2018/03/21/ancient-round-coins-were-invented-to-prevent-fraud/
They made round coins as a means of fighting coin clipping, which occurred back then, too. Interestingly, Isaac Newton invented modern coin ridges (reeding), to also help fight coin clippers, and made coin metal measurements even more precise, to combat counterfitters. He eventually became head of the British Royal Mint in the late 1600s.