This mod adds the Iron Coin, the Emerald Coin, the Diamond Coin and a bag:
100x Iron Coin = 1x Emerald Coin
100x Emerald Coin = 1x Diamond Coin
You can convert its on the bag, all converts can be reverse with de "-" buttom:
Inside the bag the coins can stack up to 100:
All items of this mod (Coins and bag) are inmune to fire and lava.
The only item you can craft is the bag:
Obiously its required on both sides (client and server).
Please let me suggestions & bugs on comments :D