Do you think this would details based on the 2:30 mark on reverse or is it a die crack? http://www.ebay.com/itm/1860-Silver..._Individual&hash=item35be40f065#ht_483wt_1204
The pictures the seller took are not that great. But I would have to say that is definitely a gouge and not a crack. Just my quick general observation, and I didn't have to think about it or examine the coin for a while.
Judging by the awful photos, I don't think the mark is in the metal at all but part of the tarnish. IMO, this coin and listing both have too many red flags. PS: if the metal is disrupted, it's definitely not a die crack. I also see some faint, newer-looking scratches crossing over the dark mark on its left end. Can't tell if they're going (sinking) into the dark mark or not.