I would like to change my answer (I got greedy)
I would use each stone to wish for another tablet, several people made the accurate point that you have not prohibited this.
As before every stone (Or piece of the stone so I can split them) will become a stone with an effect it gives by holding it (and in some cases wishing whilst holding it)
The first 3 stones would become the Super Set
1) A stone that will transport you anywhere in space when you hold it just by wishing it (Teleportation)
2) A stone that will transport you anywhere along your own timeline by focusing on it (Time Travel - See "About Time")
3) A stone that would restore whoever held it, both mentally and physically.
The second 3 stones would become the Understandings Set
1) A stone to obscure understanding
Obscure your presence and people will see you but not understand that you are there, obscure your name and people will know you but always draw a blank when trying to say your name, obscure the cold and people will shiver but not make the connection to being cold.
2) A stone to share understanding (Both must be holding the stone)
You share what you choose to share, but you can only share truth, and the recipient understands this. Share your intentions, your feelings, your wants, your memories, your knowledge-based skills, all with perfect clarity and understanding.
3) A Stone to accumulate understanding
Memorise any book with 1 read, learn any skill or instrument in a week, master it in a month, epitomise it in a year.
The last 3 stones would become the Immortal Set
1) The Timeless Stone
As long as you wore it and wished it, you would remain young and healthy (barring serious or fatal injury)
2) The Pocket Reality Stone
As long as you wear it you can create a pocket reality you can retreat into, like a daydream except real, you cant take any objects or material out of it, except what you brought in, and no time passes outside whilst you're inside.
3) The Truth Stone
Ask it any question and receive the truth.