The 22-year-old winger enjoyed two extremely successful loan spells at Wetherby Road, helping the Sulphurites to promotion from the National League in 2020/21 before finishing last season as their joint-top-scorer with 14 goals.
Unsurprisingly, Town were keen to bring Diamond back to North Yorkshire once again ahead of what will be their third League Two campaign, though the Black Cats were not willing to play ball on this occasion.
The Gateshead-born attacker is contracted to Sunderland until the summer of 2024 and now looks set to be loaned out to a League One side next term following the Wearsiders’ recent promotion to the Championship.
“I would say Jack Diamond coming back is unlikely now, but we really did try,” Weaver told the Harrogate Advertiser.
“We had a good go at getting him back here again. We’ve tried to sign him on a permanent deal but got knocked back. We’ve tried to bring him back on a loan basis, on any basis we could to be honest.
“We've tried, but Sunderland own Jack, he is their player and we have to respect that.
"With regard to the loan, they've said to us that they want to see the lad tested at League One level now that they have gone up to the Championship.
"Obviously it is disappointing because Jack Diamond is a real talent and he made a big impression during his time here. But, we are excited by the transfer business that we have already done this summer and the other deals that we are still currently working on.”
So far this summer, Town have recruited goalkeeper Pete Jameson, defenders Kyle Ferguson, Joe Mattock and Jaheim Headley (loan), plus midfield duo Stephen Dooley and Josh Austerfield (loan).
Those additions have boosted Weaver's squad size up to 18 players, though Aaron Martin, Nathan Sheron and Leon Legge have all been placed on the transfer list and are expected to leave the club sooner rather than later.