That said, I was never really one of those referees who saddled his players with a funerary boat made of solid gold and took big to fit through the doors of the burial chamber where it was kept or a dragon's trove consisting entirely of copper pieces in the millions. I liked to toy with my players, of course, and test their ingenuity, but I preferred to go the route of simply making ordinary things like coins, gems, or jewelry sufficient weird that it took cleverness and perseverance to be able to be able to cash them in.
I used to have a formula for the way I determined the likelihood that monetary treasure was unusual in some way, but I can no longer recall it. So, I'm going to borrow a page from Matt Finch's Swords & Wizardry and go with the following:
For every 100gp in value, there is a 10% chance that 100gp worth of monetary treasure is unusual, AND
For every 1,000 gp in value, there is a 10% chance that 1,000gp worth of monetary treasure is unusual, AND
For every 5,000gp in value, there is a 10% chance that 5,000gp worth of monetary treasure is unusual.Remember, of course, that "monetary" here means treasure whose value to the characters is expressed entirely in how much cash it can bring through its sale. I never used this method when dealing with weapons, armor, and other such things, because there already were tables to determine their unique properties, if any.
For every Xgp worth of monetary treasure determined to be unusual, roll on the following table to determine in what way it's unusual:
1 Unusual Shape (e.g. triangular coins or square gems)
2 Unusual Size (e.g. giant-forged coins or small bead-like gems)
3 Unusual Color (e.g. green gold pieces or blue rubies)
4 Unusual Markings (e.g. strange glyphs on coins or carvings on the surface of gems)
5 Unusual Property (e.g. glowing coins or floating gems)
6 Hazardous Property (e.g. coins coated with contact poison or gems that give off radiation)
Except for number 6 on the list, all of the other unusual qualities add about 10-25% value to the monetary treasure, but the characters have to work hard to get someone who will be willing to buy them. After all, how many fences have ever heard of blue rubies and would recognize their value when he did? The intent here is to spur side adventures and visits to sages and esoteric collectors in order to offload the weird loot.