I am a jewelry junkie & have many necklaces. I cut straws in half, & slide the straw up the chain. The tops of the chains are all together, either tied by a twist tie or on a hook in a traveling jewelry case. The straws keep the chains from tangling & keeping the chains tied together at the top, only untying them to switch necklaces, really works-I drove to canada from the midwest with 40 necklaces all in straws & no problems at all with tangling!
You can place just one or two in small sandwich ziploc bags. You can also wrap the necklace around something like a pencil. Or, you can fold the necklace onto itself, like a zigzag fold, leaving the last bit of the necklace to use it as a loose tie around the bundle you have created, and hook the clasps so that the bundle stays in tact.