This transparent pale blue green gem is worth 50 gole and contains a portion (DM's discretion) of a Marid's power

As such it can grant uptp:

+3 to Dex Saving throws

                 or

+4 to either Wis or Cha saving throws

Additionally, if the Marid wishes it can grant use of either any of its resistances or if carrier is dropped to 0 hit points but not killed outright

 Acid (Requires Hostile creature to succeed on a Dex save equal to the carrier's spell save DC or take1D6+ carrier's spell casting modifier Acid damage) 

2 Lightning (Hostile creature must succeed on a Dex save equal to the carrier's spell save DC or take 6D6+ carrier's spellcasting modifier in Lightning damageon a failed save or half as much on a successful save and items worn or carried not made of metal ore directly ignited and their wearer must remove them or hake 3 D6 fire damage)

3 Thunder (Requires Hostile creature to succeed on a constitution save equal to the carrier's spell save DC or tak 2D6+ carrier's spellcast modifier in thunder damage and be pushed 10 feet from carrier on a failed save or half as much damage and not pushed on a successful save.

Furthermore, a thunderous boom can be heard four up to 300 feet)

Notes: This gem requires the carrier to attune for 8 D10 + 4 hit dice (on maximum x2) hours