Line baking sheet with foil. Stir chocolate in top of double boiler set over simmering water until melted and smooth (do not allow bottom of bowl to touch water). Remove from over water. Using back of spoon, spread chocolate over veined underside of 1 leaf; wipe away any chocolate that drips over edge. Place leaf, chocolate side up, on prepared sheet. Repeat coating with remaining leaves and chocolate. Refrigerate just until chocolate sets, about 1 hour. Carefully peel chocolate leaves off lemon leaves. Return chocolate leaves to same sheet. Cover; chill up to 1 week.