Do C Diem boots have any identifying marks I can look for?
The ones I got on ebay are beautiful, fit like people have described here, but have absolutely no branding in/on them at all. They were also almost brand new, they had only been tried on and the black coating on the soles wasn't worn off. I put more wear on them in the hour I wore them around the house then they had when I got them.
If they are "vintage" like the seller described and made many years ago as a custom boot, it is be possible they were made by the same bootmaker that makes C Diem but not branded as such, or they may be a recreation...
Also, the boots I got have no rubber on the heel to wear and replace, so I dropped them off at the cobbler to get Vibram soles on both the heel and forefoot.