Mr Crichton's wealth has come from success in the automotive business. Last year he was valued at $165 million, and that's now climbed to $175 million.
Mr Crichton, 67, who is a champion sailor as well as a successful businessman, was made a Companion of the New Zealand Order of Merit for services to business and yachting in this year's Queen's Birthday honours.
The Sydney-based Kiwi migrated to Australia in the early 1980s where he founded Ateco Group, which today imports Ferrari, Maserati, Alfa Romeo and Citroen vehicles into New Zealand and across the Tasman.
Rotorua Boys' High School principal Chris Grinter said the school still had a lot do with the pair who continued to give their support, financially and in other ways.
"They are great supporters of the school.
"We value an ongoing relationship with both of them because of the stories they can tell and the expertise and motivation they can provide to our boys."
Mr Grinter recalls three students being flown to Dunedin in 2008 with Mr Colman to meet potential investors and business mentors after they formed a company, Tangaroa Engineering, with classmate Henry Genefaas as part of the Lion Foundation Young Enterprise Scheme.
The trio, who invented solar-powered, reusable glow-in-the-dark fishing lures, went on to win the award given by the Lion Foundation.
The first person they called after winning the national award was Mr Colman.
Two years ago the school fundraised to take two rugby teams to Argentina and they held an event at which Mr Crichton spoke and provided a number of items to auction.
The event raised $20,000.
Another Rotorua business owner, property entrepreneur John Sax who owns the award-winning Treetops Lodge, is ranked 108 on the rich list and is worth $85 million.
Bay of Plenty-based Colin and Dale Armer are in 49th place with a worth of $200 million. They control 58 South Island farms and 13 North Island farms near Te Puke, where Colin bought his first dairy herd.
Prime Minister John Key's $50 million puts him at 157 on the list.
New Zealand's Top 10 rich list
1. Alexander Abramov $7 billion
2. Graeme Hart $6 billion
3. Richard Chandler $5 billion
4. Julian Robertson $3 billion
5. Todd Family $2.7 billion
6= Christopher Chandler $1.5 billion
6= William (Bill) Foley $1.5 billion
8. Eamon Cleary $1.2 billion
9. Dowager Duchess Henrietta Bedford $1 billion
10. Goodman Family $950 million
