John Knight, the oldest son, came back to Kaitaia after Keith's death in 1958 and took over the reins, eventually purchasing the business.
He then sold it to Keith and Alice's youngest son, Monty Knight, in 1986 and he runs it with the help of his youngest daughter, Adeline, who has worked in the shop for the last 10 years.
"She wants to buy the business so in future I hope to be able to sell it to her," Mr Knight said.
He employs a lot of part-time workers, including secondary school students and mothers. "But we've always had good staff - the job is pretty demanding and we set a high standard but we attract a high calibre of people who have worked for us over the years."
He says there are other considerations. "We have a duty to offer young people good training - they might go away and become a brain surgeon but they need the self discipline and commitment that comes from having an after-school or holiday job in places like our jewellery store. Every employer should have something like that on their programme."
Mr Knight has also owned the Okahu Estate vineyard for 35 years, but describes making wine as a "labour of love, a passion rather than a money-making concern".
- The store is offering a range of promotions as part of the birthday celebrations.
"The festivities continue until July 30 and then I only have to wait another 15 years to celebrate the 100th," Mr Knight said.
