"I've achieved everything I want to in the sport and I'm just here to enjoy playing this week. But in saying that, I still want to play all eight days," he said.
Ironically, Diamond said his form had been patchy in the build-up to the nationals but "it's getting better".
Anderson, 20, of the St Andrew's club conceded after the eighth end of the final.
"Ashley was just too good and I couldn't get into the final."
An indoor bowler for nine years, Anderson won the Truth Cup for the woman to do the best in singles play. All three other females were eliminated in the last 16.
Anderson had previously won the Cliff Thompson Trophy for the most successful junior five times and is the first person to win both trophies.
"My long-term goal is to represent New Zealand. I've been a reserve in the past," she said. "Hopefully, I'll make some more finals this week to push my case."
Diamond beat eight-time national champion and last year's winner Grant L'Ami of North Taranaki 12-8 in his semifinal, while Anderson beat Lloyd Bellis of Nelson 11-4.
Bellis won the Kath and Sen Smith Trophy for the competitor over 65 doing the best in singles play. Fourteen-year-old Aidan Zittersteijn of North Taranaki was the best junior, after winning a three-player round robin when all three were eliminated in the last 128.
Pirimai's David Vesty was the best of the Hawke's Bay players. Vesty reached the last 32, where he lost 10-9 to Aucklander Ray Wyatt. Pairs section play involving 310 teams, 21 of them from Hawke's Bay, will be played today.