Raphy's Coins is a mod of currency, for player trading and shops but it can also be used to make emeralds, by crafting the coins into emerald coins and trading them with a fletcher.
Theres also coin sachels that can be dropped from zombies and give rusty coins, that can be polished to turn them into regular coins.
Also the coins can be crafted to make higher grade coins like 5 copper coins used to craft 1 iron coin.
and 2 iron coins to craft 1 gold coins and such.

