I have a character who comes into a massive amount of cash. It's earned illegally through pushing/ manufacturing drugs, so for someone to just empty a huge amount of money into their bank account would definitely raise some suspicion. The character has always had a low level job his whole life, is young, and could in no way get this much by any traditional means. He keeps it in his home or just around places he frequents. At one point, he decides it is safer to hide his riches, but the quantity has grown so much by the first time he thinks of this idea, that hiding it is no longer an option. He decides to convert it. One friend of his who has "connections", to say it plainly, can do this for him. Gold is his first choice, but obviously it won't work. Gold bars are hard to come by, they take up space, there'll be a lot of them, and they're heavy. Gold is unconventional because of its inconvenience. More importantly, its value changes. I'm trying to decide what material/ substance/ item is valuable enough to use as a placeholder for all the money, just for the time being. Something that can be "redeemed" and the value will not change (Or seldom change) and will rise if anything.