They appear authentic.
One would expect a friend would inform you of the coins' authenticity. Ask your friend. Then ask him how he knows.
This is an opportunity to learn more about a topic your friend thought you might enjoy and share experiences learning and exploring numismatics. Related topics of history, economics and metallurgy transform from lifeless classroom lectures to fascinating hands-on play.
With the uncertainties of counterfeiting, these topics can equip you for better selection, purchase and sales decisions.