Prismarine Crystals — Minecraft item

Overview

Prismarine Crystals are the glowing half of the ocean's material set: four prismarine shards and five crystals make a Sea Lantern, which emits light level 15, works underwater where torches cannot exist, and never breaks when flooded. That makes crystals the item that lights every underwater build in the game. Guardians drop 0 to 2 each and elder guardians drop more, so the supply is the same monument trip that provides the shards — but the crystal-to-shard ratio matters, since a lantern needs more crystals than shards and most players run short of crystals first. Sea lanterns can also be mined back with Silk Touch to recover the block whole; without it, a broken lantern drops 2 to 3 crystals, which loses you material. Beyond lanterns, crystals have no crafting use, so everything you gather goes into lighting. A monument converted into a base ends up lit almost entirely with the lanterns its own guardians paid for, which is one of the more satisfying loops in the game. Gather crystals first and shards will look after themselves on the same trip.

Crafting sea lanterns — light level 15 that works underwater and survives flooding — which is the only practical way to light an ocean build.

Prismarine Crystals is a crafting material item in Minecraft Java Edition 1.21.4. Sixty-four fit in one inventory slot. You get it by killing Elder Guardian and Guardian.

It also turns up in chests in Buried Treasure. It goes into exactly one recipe: Sea Lantern.

About the prismarine set

How to get it

Kill guardians for 0 to 2 crystals each, up to 5 with Looting III, or break a sea lantern without Silk Touch for 2 to 3. Each sea lantern needs 5 crystals and 4 shards.

Tips

You will run out of crystals before shards; a lantern needs 5 crystals to 4 shards, so gather accordingly.
Mine sea lanterns with Silk Touch to move them intact; breaking one without it loses material every time.
Elder guardians drop more than ordinary guardians, so clear all three before setting up a farm.
Sea lanterns are the only light source that cannot be washed away, which matters in a flooded monument.