The elf-stone is generally found near a rath; it has great virtues, but being once lifted up by the spade it must never again touch the earth, or all its virtue is gone. –source
The ancient arrowheads, called elf-stones by the people, are used as charms to guard the cattle. –source.
A young man lay down to sleep one Friday evening in summer under a hay-rick, and the fairies must have carried him off as he slept; for when he woke he found himself in a great hall, where a number of little men were at work–some spinning, some making shoes, some making spears and arrow-heads out of fish-bones and elf-stones; but all busy laughing and singing with much glee and merriment, while the little pipers played the merriest tunes. –source
The Elf stone (fairy stones) can be found either near a creek or a fairy rath. They appear as either smooth stones or rough arrow heads. The stones have amazing magical properties used for healing, blessing, and empowering. These stones were forged by the fairies themselves and used either as weapons or tools of the arts, and once picked up they should never touch the ground. It is believed by some that the stones should never be touched by mortal hands, or their power will fade away and become useless. Rather, it should be picked up with a spade or a sacred tool, though it should not be made of iron. The fear is that the iron would repel the magic and power left behind by the fairies that carved the stone.
For me, I would place them within a mirrored bowl filled with water from a well or creek. It would help prevent them from losing their power from being touched or dropped upon the floor, and the water would become empowered from being in contact with the stones.
Water blessed by elf stones would be fantastic for healing, purifying, and to create a place sacred to fairies. Placing the water on a shrine or altar dedicated to the fair folk would add a great deal of power and attraction. The water would also be great for warding away harmful fairies as well, especially boggarts or cruel goblins.
Elf Stones are a great remedy against fairy ailments like the fairy blast, fairy dart, and even against their evil eye. You could create an amulet from the stone to promote good health and luck in your life.
As a fairy doctor, I would love to use them as tools of healing either by using them to bless water and ointments, place them upon rattles to use for prayer, or use them within charms to give to those who are tormented by fairies.