They give +1 resistance bonus (10,000g) to all saves and you can stack up to 5 of them for a +5. Cracked gives +1 resistance bonus to 1 save (3,400) and you can stack up to +5. Flawed gives +1 resistance bonus to all saves (6,000g) and you can stack up to +3.
That being said:
The Advanced Ioune Stones (from Seeker of Secrets) are NOT legal for society play, unless they appear on a chronicle sheet. I am looking for a list of all the PFS chronicles that have them as treasure though. Just played "Mists of Mwangi 0-5" last night which gives access to a flawed and a cracked Advanced Ioune Stone. If there is a chronicle that allows the purchase of Amber Spindles, I would definitely like to know its name, so I can set up some tables for it in Reno, NV.
