It's a Byzantine 12 Numi from the Alexandria mint of either Justin I (518-527) or Justinian I (527-565). That's in pretty decent shape for this sort of coin, though the style looks a bit odd (you might want to check authenticity elsewhere, though this would be an odd coin to counterfeit). If you want a rough idea of value put "Justin Alexandria" or "Justinian Alexandria" into a search on VCoins (make sure you set it to check "match all words" in your search).
Its genuine. Many early Byzantine coins look a bit outlandish and crude compared to their earlier Roman counterparts.
Some more info: Justin I, 12 nummi, Alexandria mint, 518-527 AD, References - Sear 112, Dumbarton Oaks 58
Yes you are right! Strange I think, how they lost in craftmanship. Thats why I wondered if this coin was genuine.
