A Masterpiece Token is an item that you can use instead of sapphires to make a Masterpiece! These tokens can be placed in your den and can be traded.
You can buy Masterpiece Tokens in the Sapphire Shop by clicking on the Den Items store table (it has a chair on it).
Some Jammers like to trade their Masterpiece Tokens so ask in-game to see if anyone wants to trade you one for an item. Head to the Art Studio in Coral Canyons to find Jammers looking to trade!
Get out there and make some awesome artwork!