Is a diamond grading report still valid after a diamond is recut and set into jewelry?

I got the diamond on my engagement ring recut (after my divorce) and made into a diamond pendant for a necklace. Is the diamond grading report that came with my diamond engagement ring still valid?The jeweler who did the resetting of the diamond told me that the diamond certificate wouldn't be valid anymore and that I should get a new one, but I don't see why not. It's the same diamond after all.