Where is the amulet coin on platinum?

The "Amulet Coin" is not an item in Platinum. You may be thinking of a different item, or a different game entirely.

Could you please clarify:

* What game are you referring to? (It's important to specify the game to get the right answer!)

* What is the function or purpose of the item you're looking for?

Once I have more information, I can help you find what you're looking for!