Philosopher's Stone
From Jenny Everywhere Wiki
The Philosopher's Stone was a legendary artefact, supposedly capable of turning lead into gold and granting immortality. Creating such a Stone was commonly considered the primary object of alchemy.
In Reality Z-25 31-H, a genuine Philosopher's Stone was created “thousands of years ago” by the “alchemists and Levite priests of Israel”. Taking the form of a large, diamond-like piece of quartz, the Stone would go on to attract the misnomer of “Solomon's Diamond”. (COMIC: Nula! Naked and Alone!)