How does the Clearing & Settlement process work in Open Transaction From what I have read and understood. As open transaction platform uses coloured coins. The issuer of the coloured coin can associate it with a particular asset: like a ticket to a concert, or gold or real estate etc. 
Now the issuer can trade these coloured coins on the open transaction platform. 

Now the question I have is:
Who manages the settlement and clearance process? That is who insures that the physical ownership of the asset that was represented by the coloured coin and transacted on the platform is transferred to its new owner?

As an example. The coloured coin represented gold. I as an end user purchased the coloured coin paid the owner the desired price. The open transaction records that I am now the Owner of this gold (courtesy of the coloured coin). However how does the physical settlement and clearance take place? What if the seller refuses to handover physical ownership of the gold?
However how does the physical settlement and clearance take place?


It depends on the settlement policies of whoever issued the asset.


  What if the seller refuses to handover physical ownership of the gold?


Take them to court, I guess?