Hatch the Stone from the Egg

When a wizard wishes to create the magical item known as the philosopher's stone, he must first discover its alchemical formula, which tells him the necessary ingredients and the method of preparing them. This information is not provided by this spell, and this spell is useless without the formula. (The exact ingredients and formula are decided by the Dungeon Master and must be discovered by the wizard by adventuring.)
When the formula has been discovered and the ingredients prepared, the wizard enchants the alchemical mixture with the Enchant an Item spell.
Hatch the stone from the egg is then cast upon the mixture. This spell slowly transmutes the mixture into its final form as the philosopher's stone. The process is completed with a Permanency spell.
The material component for this spell is an enchanted retort used to hold the alchemical mixture. The egg is not destroyed upon completion of the spell and may be used again. Further details about the philosopher's egg are found in Chapter 4 of The Tome of Magic (DM's eyes only).

[Tome of Magic]

School: Alteration, Enchantment/Charm, Evocation
Level: 7
Rarity: Uncommon

Range: Touch
Components: V, S, M
Duration: Special
Casting Time: 1d4 +4 hours
Area of Effect: One alchemical mixture
Saving Throw: None

Material Components:
a magical item known as the philosopher's egg