Jewelry Purple Stones

What are some neat wedding ideas for an outdoor wedding in May by the lake, with a nature theme sort of?
My fiance and I love plants and nature and we’re having an evening wedding at his parent’s house by their lake, with all sorts of lights/candles.Oh we also like stones, like amethyst, sapphire, moonstones and tiger’s eye and we wanted to incorporate those into the wedding somehow, how could we do that? As favors or gifts, or some sort of decoration with any of the above mentioned. We’ve thought of jewelry, maybe get some amethyst necklaces but what else could we do? Our colors are blue, purple, white and green
Your ideas already sound great. For favors you could do tree seedlings and put them in a pretty jar. Or flower seeds and a monogrammed mini pot to plant them in. Those would probably be cheaper than giving everyone jewelry and more in line with a nature theme. If you guys love plants, why not share it.
You can also add colored sky lanterns to hang above you. That would look great with the lights and candles.
Amethyst Gems, You Can Have Saturated Rich Purple Color In Amethyst Gem Stones