You can't reproduce cracks like that with casting. From the pictures, looks to be OK. Lettering reasonably sharp, no evidence of tooling, sharp edge of chip at 4 o'clock reverse suggests genuine. Nice orichalcum (zinc rich copper alloy) color.
I feel reasonably sure that this coin was struck at the lower end of it's alloy paste range temperature.
I normally examine such cracks with a high powered lens, looking inside the crack, hunting for tensile metal distress and sharp edges. Can't do this with an eBay coin.
Matt, again I'm fairly new at collecting so my opinion that it's genuine - should be taken with a grain of salt. I'm really posting to let you know of two sites I always check before I post for opinions and suggestions.
P.S. I found two fakes using these sites in the past month.