Are you looking to use these for or just for a cool base decoration ? Minecraft: End Crystal Display Case Tutorial
If you want to create your own "glaring" display or use them for Crystal PvP, follow these steps according to the Minecraft Wiki: Glaring End Crystal
: Players can craft them and place four on the exit portal to respawn the Ender Dragon. How to Craft and Use Them Are you looking to use these for or
In Minecraft, End Crystals are powerful entities that play a critical role in the End dimension: Glaring End Crystal