How do I determine the validity of a physical Bitcoin?

Could you elaborate on the steps one should take to ascertain the authenticity of a physical Bitcoin? Given the digital nature of Bitcoin, it's intriguing to consider the existence of physical representations. Are there specific markers or security features that should be inspected? Additionally, is there a reliable way to verify the digital counterpart associated with a physical Bitcoin, such as scanning a QR code or checking a blockchain explorer? I'm particularly interested in understanding how one can distinguish between genuine and counterfeit physical Bitcoins to avoid potential fraud.