Not a pretty sight, but what you can do is to use a straw.
Slide one end of the necklace into a straw thick enough, and 'close' the necklace. Keep the necklace in an air-tight box or zip-lock bag to prevent oxidisation.
It can be really frustrating when the necklace entangles. But do not tear it apart in frustration! It can be un-tangled with some patience.