The Golden Eyes of Shahr-e Sukhteh

A Golden Eye of Shahr-e Sukhteh is a ball of rubbery pitch, covered with a thin layer of gold and engraved with a circle (for the iris) and a pattern of lines that represent the rays of the sun. Tiny holes are drilled on both sides. To wear the eye you have to have more tiny holes drilled into the bones of your eye socket so that somebody can get a needle and golden thread and actually sew it in.

this is a .gif, for some reason i don't fully understand

All of this is true. (Well, I'm not an archeologist, it's an obscure thing that somebody got very excited about on Wikipedia). What is not true, but might be cool maybe is the following:

• About a third of all people who get the surgery also get an infection and die (okay this might be true).
• The first stage of the surgery doesn't get you anything but a good story and a cool false eye.
• The second stage of the surgery also involves the surgeon shaving your head and making a couple of small holes in your skull, allowing your brain to make contact with the open air. Salt is offered and bells are rung to attract curious spirits, who will see the hole in your head and not be able to resist exploring it. Your head is then coated with pitch, sealing the spirits into your skull. Your golden eye will be able to see spirits, sometimes. You will also have occasional glimpses of the future, which is exciting. You have to wear the pitch cap forever.
• The third stage of the surgery involves the surgeon inserting a long thin copper rod into the small hole in your skull before sealing it shut. The copper rod pokes out of your skull and can be used to stir up the spirits. If it's touched you have a brief, horrific vision of the future. If electricity is run through it you have a sustained, horrific vision of the future. They are always horrific and always 100% true.
• The people of the Burnt City have a kind of clay jar containing copper and iron electrodes that creates electricity when it is filled with vinegar.
• The Burnt City is called that because it will one day be destroyed by fire. The gates to the city will be barred from outside, the rivers will be dammed and everyone in it will perish in pain and anarchy. Nobody knows when this is going to happen. Currently it is a wealthy trading hub that specializes in the production of board games, ivory, dice and caraway seeds.
• Children's skulls aren't as hard as the skulls of adults, so spirits find it easier to get in and out. This is why children are all mad.
• If you bind a baby's head to a flat board then its skull will grow into a different shape (this is true). Since the mind, like water, takes on the shape of its container, if you shape it right your baby will grow up to be a great leader and capable of brilliant insight. But if you shape it wrong your baby will be a coward and a fool.
• Most experienced surgeons are also experts in headshaping and command enormous prices for it. The eye thing is just a sideline for them, most frequently done on commission for a king who wants a soothsayer, and they won't just do it for free. A less experienced surgeon is cheaper, obviously, but also worse at mitigating infection.
• If a high-profile child grows up to be a disgrace then the surgeon who shaped her head is also disgraced. They might still be great at mitigating infection, however. They're sometimes sought out by poor families who want their kids to have a chance.
• If a baby's head is shaped just right, the holes are made large enough and enough sacrifices are made, the surgeon might be able to attract and trap a daeva. This spirit is very powerful and very finicky. It must find the head aesthetically pleasing and the thoughts within must be of sufficient quality (which are the same for a daeva). Having a daeva in your head makes you a mighty sorcerer, capable of seeing across all time and space and summoning creatures to you from the far depths of the universe, but having this portable Aleph makes you disengaged from the cares of the everyday world. In addition, if it is not punished through the application of electricity, the daeva will resent its captivity and try to drive you mad so you will dash your skull open and let it go.
• If you die with a spirit in your skull the spirit is still trapped in your skull and will not be set free until someone breaks the skull, which may take thousands of years. Most spirits will go mad if left underground, among the ruins of a burnt city, for thousands of years. Which is why all the visions of the future are horrific.