I just received this email from Dan Stout of Accrete Hardware:
Thanks for writing. I will ship the order to the new address tomorrow.
I will include with the order, the collar and the collar putty you will need...
You have a beautiful lamp. It was made about 1880. The jagged edge on the neck of your lamp is original.
It is never a good idea to use epoxy. If the collar ever needed to be replaced in the future, trying to remove the epoxy would destroy the neck of the lamp.