Slave Collar or Not?

An antique dealer came to me to see if I was interested in a "Slave Collar".
This looks old but is pretty crude,  
My normal thoughts are: If its crude, it is most likely a fake,

I have seen Darby style collars that I know are righteous but this one I must seek help with.  (Below)

I have my ideas about it, but just don't know.
What does bother me is how the padlock clasp is pointed inward and I would think it should be on the outermost side of the collar.
As these things were not made for comfort, maybe it would be designed for pain control. 
The dealer paid some good money for it but I just don't know.
Your thoughts?

Mark, there are very simple answers to your question. If it was put on a slave, then it was a slave collar. Whether a restraint was originally made for an animal or a human is not the point. Proof that is was used as such is near impossible. The crudeness of construction depends on the skill/lack of skill of the blacksmith. I could probably do better, but it is good enough for the job. It seems overly heavy for an animal collar, but I am also concerned that the clasp protrudes inward. Maybe that was altered later on??  I doubt you'll ever know the truth. I do like oddball things but I wouldn't pay much for it.

Darby collars, as per your first photo are usually Plug locks. I know that John Bushey owned a McColl Darby neck collar, otherwise I have never known of another, apart from chrome plated repros. Happy to be proven wrong if someone has one in their collection.

I saw the seller of the collar yesterday and he informed me that since I wasn't certain about its origins (and my interest in it was uncertain), he had a buyer for it at $1,200.

Paul is correct that if it was used on a slave, that fact alone would deem it as a slave collar, but I will be happy if and when a Hiatt style one shows up at my door one day.