The actor appeared on "Tamron Hall" with his "mixed-ish" costars Tika Sumpter and Christina Anthony on Tuesday, where Hall took a moment to ask Gosselaar about Diamond's passing. Dustin, known for his role as Screech Powers on the sitcom, died at the age of 44 on Monday from small cell carcinoma cancer.
"It's always tough when someone passes away. I think it's even more so when the individual is someone you know and the age of Dustin," said Gosselaar. "It was only a few weeks ago that we heard about his diagnosis and for it to happen so quickly is shocking."
"Myself and the rest of the cast, we will get together at some point and sort of express our feelings, but yeah, it happened so quickly that we're all just pretty shocked about it," he added.
When Hall noted that the cast, who -- save for Diamond -- all appeared in Peacock's "Saved by the Bell" revival, were like "family," Gosselaar explained the "interesting" relationship he and his costars had with Diamond over the years.
"It's interesting. A lot of people may not understand that you can work with somebody for years -- you can be very close, you see this person every day for an entire season of shooting and then once things wrap, the camera stops, you just drift apart," he said. "There's no reason other than just things happen in life and before you know it, years have passed and I think that was what happened with Dustin with the rest of the cast."
"There was a time when I wasn't talking with anybody on the cast," he said, before joking that once "mixed-ish" wrapped he "may never talk to Christina Anthony or Tika Sumpter ever again."
Diamond got his big break playing Samuel "Screech" Powers on "Good Morning, Miss Bliss" from 1988-1989. That show became "Saved by the Bell," on which he starred from 1989-1993, before starring on both "The College Years" and "The New Class."
Diamond and Mr. Belding actor Dennis Haskins were the only original cast members who didn't appear on the most recent "Saved by the Bell" revival on Peacock. His character was explained away as being on the international space station with his robot friend, Kevin. After his death, Diamond's longtime manager Roger Paul told PEOPLE the late actor was "upset" he wasn't asked to be in the reboot, but had "talked to one of the executive producers about possibly coming to appear on the second season and he was happy about that."
On Monday, fellow "Saved by the Bell" costar Tiffani Thiessen shared a tribute to her Instagram page, writing, "I am deeply saddened by the news of my old co-star @realdustindiamond passing. Life is extremely fragile and it's something we should never take for granted. God speed Dustin."
Added Elizabeth Berkley on her page: "I'm grateful to have gotten to create with Dustin when we were at the beginning of our dreams coming true. I will hold onto those sweet memories and the laughs we shared. Rest In Peace."
Mario Lopez paid tribute to Diamond on "Access Hollywood" later in the day, telling viewers, "It is with a heavy heart that I announce my friend and Saved by the Bell costar passed away this morning." He added, "He was like a little brother to me and we always remained in contact over the years. I actually spoke with him a couple weeks ago after he got his diagnosis. Even then, he was full of energy and he was optimistic. Life is just so fragile and not to be taken for granted. Our prayers are with Dustin's family and his friends."