It is a Wondrous Item, very rare (requires attunement)
Normally, during wearing of this amulet, you have a chance to use an action for naming a location which you’re familiar by on another plane of existence. But then make a DC 15 Intelligence check. However on a successful check, you can cast the plane shift spell.
Even on a failure, you and also each and every creature and the object within 15 feet of you may travel to a random destination. Just Roll a d100. On a 1-60, you do travel to a random location on a plane that you named. Of course on a 61–100, you can easily travel to a randomly determined plane of an existence.
Notes: Teleportation, Exploration, Jewelry