Apprentice Ring of Blasting

A simple silver ring etched with bursting patterns worn by apprentice level spellcasters.  While worn, once per turn when you hit a creature with a ranged spell attack roll using a cantrip, the magic explodes out from the target.  Each creature within 5 feet of the hit target must succeed on a Dexterity saving throw against your spell save DC or also take the cantrip's damage.