are enchanted tools allowed?
also notch apples
also normal golden apples
any light block, something cannot hold infinite energy
an anvil: it can make items magical just by hitting with a hammer on it
any mob egg, but it isnt obtainable so idk
soul sand/ soil, sand or soil cannot hold souls
a bed
an eye of ender
a ghast tear or any other potion material
any redstone component, radioactive substances cannot propogate
chest or any other storage block, a one 1x1 or smaller cannot hold multiple 1x1

most likely because you only have a single amethyst., if you copy the build around other ones you will get a lot more shards