The stones are listed in order starting with January and include some creative alternatives toward the end of the category (e.g. Citrine for Hyacinth, and some faux alternatives after the stone options!). We referenced this birthstone info from the Wikipedia Birthstone page.

January February March April

garnet, emerald hyacinth, pearl, amethyst, bloodstone jasper, aquamarine, jade, bloodstone sapphire, diamond, opal