Stone of Jas

The Stone of Jas is a subject that very little is known about, and remains one of RuneScape's most cryptic mysteries. Apparently, the Stone of Jas was used by the gods to create Gielinor, including all life and magic upon it. It was the Stone that gave the rune essence its power.

The Basics of Magic
The stone is mentioned most prominantly in the Moonclan Manual purchased from Baba Yaga on Lunar Isle. The book details the discovery of the first rune essence at the start of the Fifth Age by a Fremennik, who's name has been omitted from the text. Brundt the Chieftain of Rellekka comments that this Fremennik was a seer of their tribe.

According the book, a Fremennik, who's name appears as "V---", stumbled upon a cave in which the stone was found. The stone's name has also been omitted and is referred to as J--. The stone was later taken, but the smaller stones, the rune essence, that surrounded it, were effected by their contact with the Stone. They could be mentally changed into elements, essentially the art of runecrafting.

The book reads:

The Writings of Melzar the Mad
The scattered pages that fill the bookcases in Melzar's Maze reveal much about his descent into madness following his escape from the island of Crandor. One of these pages mentions the "Cabbage of Jas", from which the gods created all life and magic.

The page reads:

The Oracle
The Oracle that lives on Ice Mountain will often speak in riddles, and sometimes amongst the ramblings she makes a clear reference to the Stone of Jas. She will state simply: "Jas left a stone behind."

This suggests that "Jas" was an actual individual that existed even before Guthix found the empty plane that he would make Gielinor.