Thanks, all! There is no catch/clasp/opening, it's all one long strand. The thread/string is doubled and it's strung very tight with no stretch or give, I've tried to get a good look at it - it looks like cotton but could easily be nylon. Good to know that the presence or lack of a clasp is an indicator of age. I'm leaning towards 80's now from what you all have told me, thanks again!