Let's see - green = money and Lodestones attract. It's not rocket science.
A lodestone is a natural magnet and thus, even alchemists use them to charge magickal items for ritual use.
They are used to attract things to the person using them and since these are green: healing, money and luck are what is attracted.
Two lodestones are often carried together - one to repel bad luck and one to attract good luck.
They are used mojo bags to up their potency.