Prismarine Crystals

Prismarine Crystals are items that can be obtained by defeating the Guardian mob. They are used to craft Sea Lanterns along with Prismarine Shards. Sea lanterns also drop 2-3 (up to 5 with fortune) prismarine crystals upon breaking, unless silk touch is used.

As a drop from Guardians
Prismarine Crystals are dropped by Guardians or Elder Guardians. They are rarer than prismarine shards, as they only drop if raw fish does not.

From sea lanterns
Prismarine Crystals can be dropped by sea lanterns, and 2-3 are dropped each time. This can be increased to 5 with the fortune enchantment.

Trivia

 * When killing Guardians for crystals, Looting I gives the best odds due to the interaction of the crystal drop with the raw fish drop.

pt-br:Cristais de Prismarinho