- "Stone Men? Good luck stopping the spread of Greyscale with prayer. You'd have better luck dancing away the plague."
- ―Tyrion Lannister
Greyscale, also known as "Prince Garin's curse", is a dreaded and usually fatal disease that can leave flesh stiff and dead, and the skin cracked and flaking, and stone-like to the touch. Those that manage to survive a bout with the illness will be immune from ever contracting it again, but the flesh damaged by the ravages of the disease will never heal, and they will be scarred for life.
People afflicted by the disease are often called "Stone Men", due to how it makes their skin hard and dead. Stone Men are often exiled from society to live in ruined cities in Essos, such as Old Valyria.
Greyscale makes the surface of the skin harden and calcify, but in the early stages it is still fairly thin and brittle, so the body's movement makes the hardened tissue split into a network of cracks. The pattern made by the hardened and splitting skin is similar to cracks made in thin ice, and in later and more severe stages look somewhat like patterns of scales. In later stages the hardened flesh becomes mottled grey and black as it dies, resulting in the flesh appearing to have the texture of cracked grey stone, or like grey reptile scales - hence the name "grey scale". The discoloration comes in later stages: Shireen was cured in early stages before the disease could spread beyond her left cheek, before it could become discolored.
Greyscale kills slowly, often taking many years to progress to a terminal state. Long before that, in the mid-to-late stages of the disease, the infection will spread to cover all of the victim's skin from head to toe, leaving them in agony. An infected person can survive like this for years, living in misery as one of the Stone Men.
In the very final stages of the disease, (perhaps years after the skin is completely covered with it), it starts attacking the body's internal organs, hardening them as it did the outer flesh. When it spreads to the brain, the deterioration can result in violent insanity. Most people rarely see these very final stages, however: only some of the Stone Men who have been quarantined off in ruins such as Valyria for many years have time to deteriorate to such a feral state. Otherwise, Stone Men are not thought of as violent but are pitied for their misery - though still shunned for being infectious..
Greyscale is extremely infectious, spread through touch contact with an infected person, or even spread on unsterilized objects that have been touched by the infected.
Greyscale is relatively uncommon in Westeros, though it does occur from time to time both in the Seven Kingdoms and Beyond the Wall. It is far more common, however, in the Free Cities and other parts of Essos. The number of people infected by greyscale is large enough that colonies are often established in old ruins such as at Valyria where Stone Men are dumped off, to keep them quarantined from the rest of civilization.
Gilly asks Shireen Baratheon what the disease is called that scarred half of her face, and Shireen explains that it is called "greyscale" and that she caught it as a baby but was cured before it could kill her. Gilly explains that she didn't know what its name was, but that two of her sisters had it and they both died. They were quarantined off from the other girls, but by the end their skin was completely covered in it, and they were no longer coherent but were acting like animals. At that point Craster dragged them out into the woods by a rope (so he wouldn't directly touch them), where he apparently mercy-killed and possibly burned them.
While in Volantis, Tyrion Lannister sees a Red Priestess of the Lord of Light giving a sermon to slaves in the street. She says that the Lord of Light hears the prayers of all men, king or slave, even the Stone Men in their misery. Tyrion quips to Varys that prayer isn't any more useful in curing greyscale than is trying to dance away the plague.
Stannis Baratheon explains to his daughter Shireen how she contracted greyscale as an infant, from an infected doll that he bought from a passing merchant ship from Dorne. By the time they burned the doll it was too late, and everyone said she would either die from the disease, or worse, live just long enough to become aware of the world before it was taken away from her. He was told that the best thing to do was to send her off across the Narrow Sea to live out her few years among the Stone Men in the ruins of Valyria. Stannis, however, refused to accept defeat, and instead brought every maester, healer, and apothecary he could find from both sides of the Narrow Sea to try everything they could to save her. Near-miraculously, the combination of their efforts actually managed to cure her, though the damage it had already done to her face was permanent.
As Jorah Mormont and Tyrion Lannister head to Meereen sailing through Valyria, they are ambushed by the stone men. Jorah manages to fight them off, but Tyrion is pulled underwater. When Tyrion wakes up, he finds himself on the shore, saved by Jorah. Unbeknownst to Tyrion, Jorah has been infected with the disease, having been touched on the wrist by one of the stone men.
Jorah Mormont and Daario Naharis travel to Vaes Dothrak to rescue Daenerys Targaryen. Daario notices Jorah's greyscale developing on his arm. He asks Jorah if he knows what will happen to him; Jorah replies that he knows. When they are reunited with Daenerys, Jorah reveals his infection to her, saying that he must leave for good and will take his own life before fully succumbing to the disease. However, Daenerys tells Jorah that she has not dismissed him from her service, and gives him one final command - to find a cure and return to her.
Behind the scenes
According to Kerry Ingram (who plays Shireen), originally it took about three hours to apply the full Greyscale scarring makeup to the left side of her face, and about another two and a half hours to take it off. By Season 5, the makeup team managed to get the application time down to two hours. The Stone Men that appear in Season 5 required large foam pieces that covered all of the head and shoulders, and took about four hours to apply (Shireen's apparently still took some time because it was added on by hand and very detailed, while the more severe Stone Men prosthetics were large foam pieces that could be at least partially assembled prior to application).
For Season 5, HBO released a 3 minute behind the scenes featurette with George R.R. Martin as well as the cast and crew giving an overview of greyscale and the Stone Men (click this link to view).
In the books
In the A Song of Ice and Fire novels, greyscale generally affects children, especially in cold damp climates. As it spreads, it leaves the flesh cracked and flaking, and hard to the touch like stone.
The affected hardened areas of skin also turn mottled grey and black, though Shireen's face isn't very discolored in the TV series - she has been cured of the disease, but in the novels the scars and dead tissue left behind are still grey and black. In Season 5, however, the Stone Men in Essos are actually depicted with grey and black stone-like scarring. According to behind-the-scenes featurettes for the episode "Kill the Boy", apparently this was done to show a contrast between Shireen (who had the disease cured years ago, and was only in its earlier stages before it could spread beyond her cheek) and people like the Stone Men with very late-stage greyscale, with much worse symptoms.
The disease is most prevalent in the Free Cities, though it is occasionally encountered throughout the rest of Essos and Westeros, even in the isolated lands Beyond the Wall. Shireen caught it while living on Dragonstone island off the east coast, but it has also been encountered on the opposite western side of the continent: in the Iron Islands, Balon Greyjoy's elder brother Harlon caught greyscale as a child and allegedly died from it (actually he was killed by Euron - it was not an act of mercy killing, as the wildlings do to those who contracted the disease, but of cruelty). He used to sit grey-faced and still in a windowless tower room and speak in whispers that grew fainter every day as the greyscale turned his tongue and lips to stone.
Greyscale is considered a death sentence if contracted as an adult, though children have a slightly better chance of surviving it - though only in the sense that a handful of children have occasionally been cured of the disease. The symptoms can be stayed by limes, mustard poultices, and hot baths, though this is just delaying the inevitable. Greyscale kills very slowly, leaving its victims to suffer as their flesh deteriorates. Adults infected with greyscale can live a year or two, sometimes five, and it is not unknown for a few to live another ten years, but it always kills them in the end. Blindness commonly occurs if the infection spreads across the face to the eyes. In its very final stages, the disease turns inward, causing the flesh of muscles and organs to harden and die just like the skin in the outer tissue layers. It is believed that cutting off any infected appendages can prevent it spreading throughout the body, though this treatment isn't always effective. Affected patches of flesh lose sensation: if someone is worried that they have caught the disease from an infected person, an early test before full symptoms appear is to prick the fingers and extremities with a knife on a daily basis. If that person can no longer feel the knife, it means they have greyscale. After Tyrion encounters the Stone Men in the novels, halfmaester Haldon advises him to prick his fingers with a knife, checking to make sure he didn't catch greyscale from them, and he does occasionally.
Very rarely, children infected with greyscale can fight off the infection, though they are still left disfigured. It is feared that the disease still lies dormant in such children, though maesters insist that they are not infectious (i.e. Shireen's father Stannis, Davos, and the rest of their household do not fear that they can catch greyscale from her, but this is still a common superstition about people who survived greyscale). The wildlings still consider people who survive greyscale "unclean", and will euthanize any child that shows the symptoms. The wildlings call the disease the "grey death".
There is no one, confirmed cure for children affected with greyscale - it is just that healers who try a variety of methods sometimes end up succeeding. In the TV series, Stannis explains that he brought in every maester, healer, and apothecary on both sides of the Narrow Sea to try to cure Shireen, and the combination of their efforts ended up succeeding - which is apparently also what Stannis did in the novels. None of them know what they specifically did that cured Shireen, or if it was a combination of different methods: basically, in desperation they "threw everything on the shelf" at the disease, and somehow this managed to cure her.
Maesters and septons alike agree that children marked by greyscale could never be touched by the rarer mortal form of the affliction, nor by its terrible swift cousin, the grey plague.
A large area around the ruins of Chroyane, north of Volantis, in Essos is even used as a large-scale colony for "Stone men", the name for those infected with greyscale. There are also vague rumors of men living in the shattered remains of the Valyrian Peninsula, in the ruins of Oros, Tyria, and Old Valyria itself - who might, similarly, be stone men pushed to live on the abandoned fringes of civilization - but these rumors are unconfirmed in the novels.
Greyscale has no direct real-life equivalent: it is somewhat similar to leprosy in that it tends to disfigure those infected with it, and in how society fears people with greyscale as "unclean". Unlike leprosy, some people occasionally manage to fight off greyscale, though their disfigurements never heal. In this respect, greyscale is loosely also similar to smallpox: people who contracted smallpox could recover from it, but they might be left with permanent and severe scarring. Visually the scale pattern somewhat resembles icthyosis (though that is a genetic condition, not a disease). Peter Dinklage (Tyrion) in a behind the scenes video for the TV series called it "sort of like a very vicious form of leprosy."
While Shireen Baratheon was introduced in Season 3, no direct explanation was provided for the cause of her disfigurement in on-screen dialogue - meaning that it wasn't entirely confirmed that the disease was also called "Greyscale" in the TV continuity. It was only first mentioned by name in the updated HBO Viewer's Guide for Season 4, confirming the name. It was finally identified by name in Season 5 episode 2 "The House of Black and White" when Shireen and Gilly discuss it. Gilly said she didn't know what the disease was called north of the Wall, though that is probably due to her limited contact with other wildlings outside of Craster's Keep. There was no mention in the novels that any of her sisters died from greyscale, though this easily could have happened.
It is not Jorah Mormont but another of Tyrion's companions who contracts the greyscale.