It’s called the “black money scam.” The scammer shows the victim a briefcase full of black bills. The victim is told the money has been dyed black so that it could escape the notice of customs. But to turn the money back into usable cash, you need to use an extremely expensive solution, which the scammer is happy to sell for $100,000.
A small price to pay to get your hands on millions, right? ABC has a slideshow that shows exactly how scammers turn this trick. The bills on top have just been coated with Elmer’s glue and iodine, turning them black. They’re real $100 bills. Everything underneath is just black construction paper.
The secret solution is just water with crushed vitamins. All you need is the water. The vitamins are there to make it look like some kind of special process. A pretty cheap magic trick that can cost quite dear for those who don’t see the smoke and mirrors.