For much of the past 111 years, the sparkling New Year’s Eve Times Square ball has been a signal for the 1.2 billion people watching it across the globe to dance, cheer, blow their horns, and embrace. It has become such a touchstone that it almost seems like another year can’t start without it.

The ball is the product of the Times Square Alliance and Waterford Crystal, the Irish company that’s been maintaining the 2,688 crystal-paneled orb for 19 years. The man entrusted with the crystal, Tom Brennan, 48, takes his role so seriously, that he starts working on next year’s ball in January. “We have a glass of champagne,” he said, “take a week off, and then start improving it for next year.”

Mr. Brennan grew up in Waterford, a small Viking town in the southeast of Ireland — and home of the crystal company — with a current population of 47,000 people. His father was a master glass blower for 30 years, and he used to run around the factory as a child watching him work. In 1986, when he was 16, he started to learn the craft. He recalled making a port glass as his first project. “With my uneducated eye it looked great,” he said. “But then they did a quality check, and I realized the part you hold in your hand was all lopsided.”

Mr. Brennan has improved since then. Five years ago he was promoted to the role of master artisan. With his new title came responsibility for the famous ball. “I still can’t believe this huge thing that the world watches comes out of my small hometown,” he said.