Gems of returning are items of legend, coveted by rogues and scoundrels alike. They come in various shapes, sizes, composition, and value--50 gp rubies, 100gp sapphires, etc. 

Once acquired, a gem of returning will always come back to its owner. If it leaves your possession for almost any reason (you give it to someone, it is stolen from you, you drop it, etc.), it will return to you (magically appearing in your pocket, backpack, or hand) at the end of your next long rest. 

You may voluntarily give up ownership of a gem of returning by willingly ceding ownership and transfer of the ability to another being (this is not the same as giving it to someone as payment for goods), by existing on a different plane of existence from the gem for 1 day, or through your death. Most gems of returning, it stands to reason, are acquired via the death of their previous owner. Anyone touching an ownerless gem of returning becomes the new owner.

You may roll on the table below to determine the value of a gem of returning:

1-50: 50gp
51-75: 100gp
76-95: 500gp
96-100: 1,000gp