"My 13-year-old son was very happy to see his mother's grave in its proper state as he had to leave for the first time to start boarding school in Auckland [yesterday]," Mr Watson said.
In the week before it was returned, he and his family had a "sense of optimism" about the waka.
"We were feeling really optimistic and had genuine hope that it was going to find its way back to Lisa's gravesite, so we were really relieved when it finally happened.
"What was also really cool was the small pieces of loose pounamu that sit inside the waka were also returned."
Mr Watson said the support from the public had been overwhelming.
"Ever since we made the theft public, our family has received a tremendous outpouring of support. Having it disappear was so distressing at the time, so having it returned has really restored our faith in human nature."
Ngaire Nicholson also had a precious taonga stolen around the same time from the grave of husband Norman, in the same cemetery.
She said when she visited his grave on Sunday, the blessed Maori walking stick was still missing: "I am still holding out hope that someone will come to their senses and return it to the rightful owner."