Hard to tell from the images provided what is going on there. It could be a die crack, split plating showing gray from the zinc, or the beginning of ridge ring? Or even something else? A closer view would be a great help. The glare is hiding what we need to see. Try getting you light from a low angle to a n angle more close to over center on the coin. If the light is too strong, it causes glare. If the light is not diffused, then it creates glare. So we are wondering in light, in the dark, with your coin.