Are papers with Rolling Stone? (5,8)

I believe the answer is:

water sapphire

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'stone?' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Perhaps there's an association between them I don't understand?

'are papers with rolling' is the wordplay.
'rolling' indicates an anagram.
'are'+'papers'+'with'='arepaperswith'
'arepaperswith' anagrammed gives 'WATER SAPPHIRE'.

Can you help me to learn more?

I've seen this clue in The Sunday Times.

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