Here is my Nero Sestertius. A different type, but certified genuine by Sear: It you compare it to yours, you will notice that while both coins have about the same high relief and therefore should have endured about the same amount of wear, your specimen has very few sharp details. I would therefore say that yours is most likely a cast...
Based on pictures alone no one can tell you for sure if your coin is genuine or not. It is certainly not an obvious fake. The best one can say is 'would I have bought it not?' Based on what I am seeing what I can say is I would NOT have bought that coin: washed out appearance, peculiar edge which looks too uniform. That is not a particularly rare type and examples come up relatively often for sale. I would wait for a better example.
