Crystals

Crystals in Sword Art Online are considered to be one the most convenient items, having immediate effect for recovery unlike potions and perform a variety of function outside of healing, extending to teleportation, corridors to locations, and displaying images or replaying voice messages.

Though extremely useful, they are expensive hence making people hesitant to use them. Their usage can also be prevent by a trap called an anti-crystal field, which later became normal for boss fights on the 74th floor and above.

Colors

 * Pink - HP Recovery
 * Blue - Teleportation
 * Green - Status Recovery