Letter Quest: Grimm's Journey Remastered

Potions are purchased in Story mode from the merchant and cost 100 gems each. At first you'll only be able to carry one of each, so you'll have to either use them in battle or fully upgrade your potion-carrying capacity to carry more. Fully upgraded, you can carry 5 of each, but you're given a health potion for free, so you'll need to use it to buy a 10th one.

This one will probably come naturally as long as you remember to buy potions, since you'll likely want to use potions while trying for the crystal stars. If not, you'll have plenty of gems left over after collecting all stars to use all your potions and then restock until the achievement unlocks.