spoilers for the hundred line last defense academy

takumi - ruby, deep red, a beloved stone, 9 on the mohs scale, making it a very sturdy stone

eito - considering making him a sapphire which also scores a 9 on the mohs scale. which makes sense since their only real difference (to rubies) is their color. thought that was interesting..

nozomi - pearl, usually around 2.5 on the mohs scale, i thought it was fitting since she can't use hemoanima like the others, though i am unsure if it makes sense to make her a gem too in this au

yugamu - lapis lazuli, often connected to wisdom and the truth, as well as medicine and healing

darumi - kyanite maybe, apparently the hardness depends on it's crystallographic direction, don't ask me what that means but it reminds me of her specialist skill in a way

hiruko - bort/bortz (black diamond), a perfect 10 on the mohs scale

shion - adamant, a fictional material, supposed to be unyielding/strongest

vexhness and eva - maybe diamonds? those do come in different colors too after all

takemaru - topaz maybe?

moko - spinel?

kako&ima - amethyst?

tsubasa - peridot?

gaku - ?