There are: Gold Minecoins, Silver Minecoins, and Bronze Minecoins.
9 Bronze Minecoins can be crafted into a Silver Minecoin.
9 Silver Minecoins can be crafted into a Gold Minecoin.
A Silver Minecoin can be crafted into 9 Bronze Minecoins.
A Gold Minecoin can be crafted into 9 Silver Minecoins.