Viriathus

Hello everyone, my name is Carlos and I'm new to coinpeople. I wanted to ask you a question about a tetradrachm of Alexander the Great I have. I'd like to know if it's genuine or fake. I'm asking because I've seen a coin on Wikipedia with a very similar die, although the flan and centering are a bit different. Thanks on advance! Here's the coin from Wikipedia: http://commons.wikim....jpg?uselang=es