As some stones of course ground, grit's back (4-3)

I believe the answer is:

rose-cut

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'as some stones of course ground grit's back' is the definition.
I can't judge whether this defines the answer.

'course ground grit's back' is the wordplay.
'ground' is an anagram indicator ('grind' the letters into a new form).
'back' says to take the final letters.
The last letter of 'grit' is 't'.
'course' is an anagram of 'rosecu'.
'rosecu'+'t'='ROSE-CUT'

Can you help me to learn more?

(Other definitions for rose-cut that I've seen before include "Hemispherically-faceted style (of diamond)" , "(Of gem) finished with triangular faces" , "(Of a gem) having tiny triangular facets" .)

I've seen this clue in The Guardian.

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