Looks just like contemporaneous portraits of Helios or Apollo, the Sun God in the Greco-Roman pantheon. Plus, if it dates back to the time of the Jerusalem Church, which was very Jewish in its orientation, the idea of making a portrait of the Messiah would have been deeply contrary to their beliefs. Iconography of Christ came with the conversion of the Greeks and other Gentiles for whom pictorial representations of divinity were the norm.
Finally, the provenance for the item is very unclear (always a bad sign). My bet: this is a fraud.