amuletsHagstoneGlain Neidr

said HAG-stone; the Welsh name is said glyne NAY-dir

also: adder stone · witch stone · fairy stone · serpent's egg · snake's egg · milpreve · adderstane · Gloine nan Druidh · Hühnergötter

amuletBritain and IrelandWestern EuropeThe Baltic and the Slavic landsUnited Kingdom Germany Russia

A stone with a hole worn right through it by water, usually flint, usually glassy. Nobody makes one: a hagstone is found, on a beach or in a field, and a stone holed by human hand does not count. Most are hung on a loop of string or red ribbon and put where the hole can be looked through.

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English hag 'witch' + stone; the parallel English name adder stone comes from the claim that snakes made it. Welsh Glain Neidr is 'snake's gem', Cornish milpreve, Scots adderstane, and northern Scottish Gaelic Gloine nan Druidh 'Druids' glass'. In Germany the same stones are Hühnergötter, 'chicken gods'.
Folk etymology, labelled as one: Pliny the Elder records the Druids' account: massed snakes make the egg out of slime and spit, and eject it into the air with their hissing. A second folk account has it come from a serpent's head, a third from an adder's sting. cited

When

first century CE to now still carried cited

Period	Roman to the present
How the date is known	textual — a dated text describes it
Note	Dated from Pliny the Elder's account in Natural History book XXIX, which is first-century. The source gives no publication year, so the start is the century, not a year. The English nightmare-charm is attested from at least the fifteenth century and the practice is recorded into the 1980s.

Years are stored astronomically — 1 CE is 1, 1 BCE is 0, 500 BCE is −499 — and printed the way a reader says them. How these dates are made.

The thing itself

Form	Pendant
Made of	Flint · Thread and cord
Goes	At the neck · On a wall · At the door
Made by	nobody — a stone shaped by human intervention is not counted as one
Colour	grey · white · brown
Retired	no — it is kept
Note	Pliny describes the one he saw as round and about the size of a moderate apple. That is a description of a Gaulish object he was shown, not a measurement of the flint stones British collectors pick off beaches, so it is not entered as a length.

What its carriers say it stops

Reported, attributed, not tested here. Each row below is somebody's claim, with their name on it.

A court case or an official citedsaid by the Druids of the Gallic provinces, as reported by Pliny the Elder
The possession of it is marvellously vaunted as ensuring success in law-suits, and a favourable reception with princes
Demons and night-hags citedsaid by Reginald Scot, printing the cure for the night-mare in The Discoverie of Witchcraft, 1584the mare is the night-hag that sits on a sleeper's chest; the charm is against her, not against bad dreams in the modern sense
hang a stone over the afflicted persons bed, which stone hath naturallie such a hole in it, as wherein a string may be put through it
Harm to livestock citedsaid by Thomas Blundeville, 1565, citing an older English writer, on hanging a naturally holed flint above a horse
Bad luck, unspecified citedsaid by a woman in Essex, to researchers in 1984
I still keep stones with holes in them on my window-sill for luck
Harm to a house or a field traditionsaid by Russian folklore, in which the stones housed the Kurinyi Bog and were placed in farmyards against the Kikimora

The story

The oldest account is Roman and second-hand. In Natural History book XXIX, Pliny the Elder reports what the Druids of the Gallic provinces told about the anguinum: snakes twist together in summer, the slime and foam they secrete hardens into an egg, and their hissing throws it into the air, where a man must catch it in a cloak before it touches the ground and then flee on horseback until a river is between him and the snakes. They said it could be tested by setting it in gold and seeing whether it floats upstream. Pliny says he has seen one — round, about the size of a moderate apple, its shell cartilaginous, covered in cup-like marks. He also says what it was carried for, and how that ended: "The possession of it is marvellously vaunted as ensuring success in law-suits, and a favourable reception with princes", and a Roman of equestrian rank from the territory of the Vocontii was put to death by Tiberius for having one in his bosom during a trial.

The English record is about sleep. English folklore collectors record the same use of a holed stone hung over a person or a horse against nightmares, attested from at least the fifteenth century. Reginald Scot printed the cure in The Discoverie of Witchcraft in 1584: hang over the bed "a stone, which stone hath naturallie such a hole in it, as wherein a string may be put through it, and so be hanged over the diseased or bewitched partie; be it man, woman, or horsse." Thomas Blundeville had already written it into a 1565 book on horsemanship, citing an older English writer, with a verse to be written on paper and hung up with the stone.

The practice did not stop. Edward Lovett, collecting folklore in Surrey and Sussex, reported in 1928 that the favourite objects for warding off nightmares were horseshoes and natural perforated stones, common on the beach at Brighton, and that the stones were usually on a loop of red ribbon or string, "or are occasionally simply hooked on to one of the knobs of the bedstead." A woman in Essex told researchers in 1984: "I still keep stones with holes in them on my window-sill for luck. I used to pick them up as a child from the beach in South Shields, and all my family still pick them up--because we think they're lucky."

The same stone does other work elsewhere. In Welsh folklore the Glain Neidr are made by a congress of snakes in spring, most auspiciously on May Eve. In Russian folklore the holed stones housed spirits called Kurinyi Bog, the chicken gods, who guarded hens and were set in farmyards against the Kikimora.

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How it is made and carried

Found, not made. Picked off a beach or out of a ploughed field, strung on string or red ribbon, and hung: over a bed, over a horse, on a door, on a windowsill. Several sources say the stone works best used together with a spoken or written charm about Saint George. Nothing is done to charge it and nothing is recorded about retiring it; a hagstone is kept.

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Now

Still picked up and kept, and sold online and in shops that sell crystals and folk charms. The Hastings legend attached to it is live enough to name: the town is said to be under Crowley's Curse, which compels anyone who has lived there to return, and which can only be broken by taking a stone with a hole through it from Hastings beach.

inference