Three Diamond rarity cards require 120 Tokens, One Star cards require 400 Tokens, while Four Diamond cards require 500 Trade Tokens.
Currently, only cards of One, Two, Three or Four Diamond rarity can be offered for trade, alongside One Star rarity.
In addition to this, if you trade cards of a Three Diamond rarity or higher you’ll also need to expend Trade Tokens, another consumable that can be earned in-game.
For example, you will receive 100 Trade Tokens for junking a One Star card, but it will cost 400 Trade Tokens in total to trade for another One Star card.