Philosopher's Stone

The Philosopher's Stone is a Hardmode Accessory that reduces the 1 minute Potion Sickness debuff cooldown time by 15 seconds, so that the cooldown is only 45 seconds. Essentially this means that most regenerative Potions can be used more often. It is dropped by Mimics.

Trivia
The Philosopher's Stone is also a reference to the anime series Fullmetal Alchemist and Fullmetal Alchemist Brotherhood.
 * The Philosopher's Stone is a legendary alchemical substance that could transmute base metals into gold or silver, and provide eternal youth and immortality. In alchemy the color crimson represents the stone.
 * The stone resembles in shape and color the one in the Harry Potter saga, shown in the first movie.