If you are wearing a nacreous gray sphere ioun stone to suppress the effects of aging, and it is temporarily dispelled or removed, does it continue to suppress your aging penalties once returned to its normal state?
From the item's entry:
"This stone protects you from ability score penalties from aging and you cannot be magically aged. Any penalties you have already incurred remain in place. Bonuses still accrue, and you still die of old age when your time is up. If you lose the stone or its abilities are negated in some way, all age and penalties apply immediately."
Once back to normal state it would stop future aging and penalties but not undo what happened when it was dispelled. This is in contrast to the flawed where it addresses removal and re-application:
"Flawed: Protects wearer from appearing older but does not protect against ability damage from aging. The stone remembers the wearer’s age at the time he first wore it and always restores his appearance to that age, even if he hasn’t worn it for years or it has been worn by other people."