what is the gold/brass open front Celtic/Druid choker necklace sometimes seen worn by the God Lugh?
The open ended choker is called a torc. http://www.ask.com/wiki/Torc
It is called a torc.
The gold choker necklace is known as torc or torque. This necklace is made of metal strands that have been twisted together to form different designs and it is made for a permanent wear.