Also known as Witch Stones, Fairy Stones, Holy Stones and Eye Stones, are stones with naturally formed holes running clean through them. These holes are usually formed by centuries of wave action and/or dripping water. It is this association with running water (which itself is said to negate the effect of evil) that is believed by many people to be the source of the Hag Stone's reputation for guarding their owner against ill-fortune and the Evil Eye. It was once common practice for people to hang these stones above the front door to their homes to keep misfortune and troublesome spirits from interfering with its inhabitants.
Smaller Hag Stones have also been carried on keyrings or worn around the neck in the belief that their wearers would secure a little of the luck associated with them. They would also be hung on bed posts at night to ward off nightmares.