I've a couple of coins that have so-called desert patinas. I tend to avoid purchasing such coins as I find judging whether the patina is authentic or artificial somewhat challenging. Judging by discussions on some message boards I'm not alone in this.
I'm interested in advice on whether the patinas for the below seem genuine or are likely artificial. For the first one I rubbed a corner of the surface gently with an ear bud and some brown/orange colour came off, although only slightly. I'm not sure if this is a food or bad sign! The other two coins have patinas that seem more hard and fixed.
I've been told the patinas are normal for these types of coin - but I would welcome more community members' views.
