Gently clean leaves using a damp paper towel. Let dry completely on a baking sheet lined with paper towels.
Heat chocolate in a heatproof bowl set over a pan of simmering water until almost melted. Remove from heat; stir until smooth. Transfer one-third of the chocolate to a small bowl; tint green. Tint remaining chocolate pale pink.
Using a pastry brush, generously coat undersides of 20 small leaves with pink chocolate and 10 large leaves with green chocolate. Place leaves, chocolate sides up, on baking sheets lined with parchment. Freeze until firm, about 10 minutes.
Starting at stem ends, peel leaves from chocolate; discard leaves. Transfer chocolate leaves to baking sheets lined with clean parchment paper; refrigerate until ready to use.