Those 'coins' are not actually gil though - those are actually Grand Company Seals (hence why each one is uniquely shaped, they each bare the face of each Company leader, and they also bear each Company's motto, such as the Gridania one clearly has written on it 'Woods Will be Done'.). There was a piece of artwork though that showed gold and silver coins on a table, amongst other things, but I can't find the pic at the moment sadly. In any event, we only have the coin icon from the game's interface to actually go on showing what gil actually looks like in Eorzea, as Moose already mentioned.