Myth: In the SCA, only knights are allowed to wear unladen chains.
Fact: This is true. (Oh! Did you see all of those feathers ruffle?)
According to SCA laws and precedents circular chains of all colors (that is, any color of chain made with open links that does not have a clasp and that does not have a medallion/charm) are reserved as regalia for members of the order of Chivalry. (Full article with citations: http://herald.poore-house.com/protocol/chains/)
All of that said.. In some kingdoms there is a custom that knights wear gold chains and squires wear silver chains. This custom ruffles the feathers of folks from kingdoms where that is NOT a custom.. And saying that the custom is wrong ruffles the feathers of folks from kingdoms where it IS a custom.
My recommendation is that if you are NOT a knight and you want to wear a chain then the correct way to handle that would be to add a clasp, a medallion or even an additional dangling link.