The actor, who played Kurt Hummel on the Fox series alongside Rivera's Santana Lopez, shared his thoughts with Variety, writing his own post remembering her as not only a great costar, but also great friend.
The article was shared by a number of other "Glee" actors, who thanked Colfer for how he was able to express what most of them have been feeling since Rivera's death earlier this month.
"How could a human being be that talented, that hilarious and that beautiful at once? How could one person be responsible for so much joy and be the subject of so many wonderful memories?" asked Colfer at the top of his tribute.
The actor praised Rivera's voice and presence, comparing her performances to "watching magic unfold before your eyes." He said "Naya didn’t just sing a song. She brought it to life."
After pointing out just how important Rivera's portrayal of Santana was to the LGBTQIA community, he also praised her "superhuman ability" to memorize all her lines -- something over which many of the show's creators and cast members have marveled.
"Even when her character was tearing mine to shreds, I couldn’t help but respect how brilliantly she delivered the insults," he added. For further proof of that, just watch the video below:
He then praised her ability to make even the worst days on set tolerable.
"On particularly rough days of filming, you might find her outside enjoying a cigarette in her bright red cheerleading uniform. She would raise an invisible glass and say, 'To being role models!' or 'City of dreams, huh?'" he wrote.
"Once, during a heated exchange between an actor and a director, I'll never forget her turning to me with a cheeky grin and asking, 'Is this a bad time to tell someone the DVD player in my trailer isn’t working?'" he added.
Calling her a great friend who'd always have your back, Colfer said Rivera "always called out mistreatment where she saw it" and wouldn't sugar coat the truth, "even if it was hard to hear."
He went on to praise her skills as a mother, saying when son Josey was born, "it was like a missing piece of Naya had finally arrived." Noting how she died likely saving her son from her own fate, he added, "Naya was an extraordinary mother until the very end."
Colfer ended his post with a quote from Rivera herself, one which went viral following her death. "No matter the year, circumstance, or strife, everyday you're alive is a blessing," she said. "Make the most of today and every day you are given. Tomorrow is not promised."