Minigolf Adventure (EP)

To obtain this achievement, you need to obtain 100 gems by playing through ARCADE mode.

You'll most likely to be naturally collecting 100 gems while working towards the 120 star achievement in Arcade mode.

If you want this quickly however... Start up the first level on *Forest* in Arcade, shoot the ball straight w/ around 70% power & you will pick up 5 gems, most likely almost every time a hole-in-one too.
Repeat said method 20 times and this achievement is yours!