There is an ancient rumor of how Alchemy came into existence:
When the gods were roaming freely within humanity, it was noticed by the humans that these gods were maintaining their youthfulness throughout the centuries.
So, once a beautiful and clever woman was approached by a god, asking her to be his consort and she replied that she will agree to it only, if the god revealed and taught her the secret of longevity. The horny fallen one was only too eager to teach her the secrets of Alchemy...
Is there truth to it? Did the gods knew about this secret and tried to keep this secret?
Like being afraid, that Adam and Eve will not also eat from the Tree of Knowledge, but also from the Tree of Life?
We can find out when we study the old scriptures.
In the Book of Enoch we find:
After the names of the leading angels are given (w. 7-8), chapter seven continues:
 And they took wives unto themselves, and everyone (respectively) chose one woman for himself,
and they began to go unto them. And they taught them magical medicine, incantations, the cutting of roots, and taught them (about) plants.
One can only assume that the major difference between Enoch and the angels is the fact that man
receives the heavenly mysteries by means of revelation, whereas angels are guilty of
exposing the heavenly mysteries to man without “God's“ permission.
In chapter nine the archangels (Michael, Surafel, and Gabriel) are observing the earth.
They beseech “God“ to do something about the evil, that is upon the earth. They say:
 “You see what Azazel has done; how he has taught all (forms of) oppression upon the earth. And they revealed eternal secrets which are performed in heaven (and which) man learned.“
Is Alchemy an eternal secret, which was not supposed to be given to man?
It looks like it, and there is, for example, the story of Gilgamesh:
Gilgamesh lost his only friend Enkidu through a decree of the gods, and he started contemplating life, death and the meaning of life. As a result he decided to find the secret of everlasting life and started searching all over the world. Finally he met Utanapishtim (Noah) on an island. Utanapishtim had been given the secret of everlasting life, as reward for his role in saving the seed of humanity in a boat. Gilgamesh knew that Utanapishtim was in possession of the secret and pleaded with Utanapishtim, so that Gilgamesh might receive the secret. But it was in vain: Utanapishtim refused.
On tablet XI of the Gilgamesh-epos, we find:
As Gilgamesh is leaving, Utanapishtim's wife says to Utanapishtim:
"Gilgamesh came here exhausted and worn out.
What can you give him so that can return to his land with honor?" (XI, 265-266).
So, Gilgamesh returns to shore, and Utanapishtim tells him of a secret of the Gods (Never underestimate the power of women!) :
"There is a plant like a boxthorn,
whose thorns will prick your hand like a rose.
If your hands reach that plant you will become a young man again." (XI, 274-276).
Gilgamesh then ties stones onto his feet, and dives into the sea. He finds the plant under water, and then cuts the stones from his feet, so that he may return to shore. He tells Urushanabi that he will take the plant to Uruk, and call the plant, "The Old Man Becomes a Young Man."
One night, when they stop to camp, Gilgamesh goes down and was bathing in the water. Then:
"A snake smelled the fragrance of the plant,
silently came up and carried off the plant." (XI, 294-295)
What does it mean : "A snake smelled the fragrance of the plant,
silently came up and carried off the plant."
In real life, no snake will carry away any plant, therefor i think it has to be understood allegorically:
Someone, represented as a snake, had stolen the plant (or the information of how to prepare the Elixir of Life) intentionally.
Who and why?
Who is represented as a snake in Anunnaki- Lore?
Enki is often depicted as half-man and half-snake.
Why did Enki steal the plant?
This plant (or information) has been stolen from Gilgamesh by Enki, in order to preserve the secret of Everlasting Life, and prevent its public announcement (which Gilgamesh had planned) to mankind.
So, according to scripture, Alchemy is real and the making of the Philosophers Stone is a secret which is eagerly guarded by the Anunnaki, seemingly up to this day.