A beautiful crystal imbued with mako.Description
Mako Crystal is an accessory in Final Fantasy VII Remake that decreases elemental damage from 
Fire, 
Ice, 
Lightning, and 
Wind by 5%.
Obtained
Mako crystal was obtained as bonus content with the Digital Deluxe Edition, and has since been made into free DLC.
Use
Being a bonus item, the mako crystal is available before the 
Elemental Materia, but pales in usefulness to it though the elemental materia can only protect against one element at a time. The 5% reduction in damage is not really notable enough for the player to use it over another accessory.