Look on the inside of the wheel on the reverse side of the spokes. There should be wheel size information as well as manufacture name/stamp. If not then there not likely genuine.
One life, LIVE IT! Get VTEC, LOVE it. Drive a Honda and ENJOY it.
Morning Wayne - I'm a bit late to this party but here's the inside of one my wheels. As you can see, branded both Honda and Enkei as well as position and some kind of other numbering (part numbers?). If there's nowt visible inside they may be knock-offs, which happens a lot out here.