Sharing two photos on IG — one from their "90210" days and the other more recent — Priestley describes why it's taken him three days after Perry's passing to find the words.
"It’s taken me a couple of days to figure out how to write this... My dear friend of 29 years, Luke Perry, was one of those truly special people who really cared," he began.
"Luke was not only a star, he was an incredibly bright light that was extinguished far too soon... and that is why I, and so many others, are in so much pain today... If you had the good fortune to know Luke, or to have ever crossed his path, I know you are sad today as well."
Jason Priestley ended his message by saying, "[T]he candle that burns twice as bright only burns for half as long... you burned oh, so brightly Luke... Goodnight Sweet Prince."
The two began their budding friendship in 1990 on the set of "Beverly Hills, 90210" where Perry played the bad boy Dylan McKay and Priestley the scholar/overprotective brother, Brandon Walsh.
Perry was 52 years old.