“He accomplished all he set out to do,” said his daughter, Wendy Weisbrot. “He didn’t feel his survival would be validated unless he could spread the word to his family and community.”

In talks to students, Mr. Diamond combined a human touch, an interest in others, a sense of humor and a keen passion for spreading the word about the Holocaust. From 1995 to 2015, he made an average of at least 15 school visits a year, often speaking to a whole grade, Holocaust Resource Center officials said.

“He pretty much had a classroom over the years that would have filled KeyBank Center, and his story was retold by those students on an exponential level,” said Beiter, an eighth-grade social studies teacher in Springville. “What I think resonated with the students was that he was roughly their age when he was sent to Auschwitz, roughly 14 or 15. That alone made his testimony very compelling.”

As Mr. Diamond’s longtime friend and fellow Holocaust speaker Sophia Veffer said, “We all should be thankful that Joe dedicated his life to tell the world what happened during the Holocaust.”