The home favourite made it 13 South African wins in 20 events since the second oldest national Open Championship in the world joined The European Tour International Schedule in 1997 and he was in tears on the 18th green as he finished his round.
That reaction came after an incredible day's play which had seen the 22 year old establish a two-shot third round lead and then move five shots clear before being pegged back and eventually finishing 14 under to beat countryman Christiaan Bezuidenhout by two shots.
Stone closed with a remarkable 71 which contained seven birdies and six bogeys but was good enough to make him the youngest winner of this event since it joined The European Tour.
The win completed a stunning few months for Stone who has long been regarded as a major prospect in his homeland.
A sixth-placed finish at the NBO Golf Classic Grand Final in early November saw him finish 14th on The Challenge Tour to secure his playing privileges and just two weeks later he claimed a maiden Sunshine Tour victory at the Lion of Africa Cape Town Open.
He then finished in a share of 18th at the Alfred Dunhill Championship in his first event as a full Member of The European Tour and this win at Glendower Golf Club gives him victory in just his 27th event.
"It's too good to be true. I'm overcome with emotions at the moment. There was a lot of ups and downs in that final round but to come out on top at the end is incredible."
Stone dropped five shots in seven holes from the fifth but insisted his belief that he could win never wavered - a belief that he had held since he first teed up on Thursday.
"I was just trying to focus on what I needed to do, there was obviously a few birdie holes after that," he said.
"After 12, when I birdied that, I was: 'Let's get going, let's get started. This is a great birdie here, let's get going'.
"The way that I've been playing towards the end of last year, I've really been practising hard during the Christmas and festive period which has really helped.
"On Thursday I felt that my game was in the right spot to compete for this week."
Daniel Brooks had held a two-shot lead around the turn after entering the final round as Stone's nearest challenger but he could not add to his Madeira Islands Open – Portugal – BPI win in 2014.
That event had been reduced to 36 holes due to weather and storms had led to delays on the first three days of this event with Brooks and Stone going out on Sunday morning to finish their third rounds with a share of the lead.
Brooks picked up a birdie on the 13th to get to 11 under but he could not keep pace with Stone who had gains on the 12th, 13th and 16th to take a two-shot 54-hole lead.
There was a turnaround of less than an hour before the start of round four but that proved no problem for Stone who looked on course to ease to victory in the early stages.
He rolled in a six-footer to get up-and-down for birdie on the second before another birdie followed after an excellent tee shot and approach to six feet on the fourth. An errant tee shot then led to a bogey on the fifth as he dropped back to 14 under.
Brooks, playing two groups behind as there was no re-draw, put his tee shot left on the second to drop a shot before making three straight pars with confidence-boosting putts on the third and fifth.
Stone then dropped a shot at the sixth after going in the water off the tee and a missed putt from four feet on the next brought the field closer with Brooks putting his first on the sixth to seven feet and rolling in for birdie.
Stone responded impressively, recovering from a wayward tee shot to find the green and get down in two on the par five eighth to restore a two-shot cushion. But a fourth bogey of the day followed on the ninth after another wild tee shot and Stone turned in 37.
Playing partner Bezuidenhout, meanwhile, was heading in the opposite direction and, after taking advantage of the second, made further gains on the eighth and ninth to get to ten under.
Brooks got back into a share of the lead on the eighth as he narrowly missed an eagle putt and tapped in to get to 12 under and the lead was his own moments later as Stone missed a slippery downhill putt on the tenth to make it five bogeys in six holes.
Bezuidenhout moved into a share of second as he made a birdie on the same hole after a brilliant approach.
Stone and Bezuidenhout then both dropped shots on the 11th to briefly hand Brooks a two-shot cushion but a bogey from the leader on the tenth kept things tight at the top.
Stone was really battling and a birdie on the 12th had him back in a share before a stunning approach to the next gave him a chance to get his nose back in front. Playing partner Bezuidenhout made a birdie to briefly make it a three-way tie but when Stone followed him in, he was back ahead on his own.
The South African pair both had eagle putts on the 15th but had to settle for birdies and Brooks moved back level with Bezuidenhout as he followed their lead with a gain on the 13th.
Stone's incredible rollercoaster of a round continued as he went from six bogeys in seven holes from the fifth to four birdies in five from the 12th with a gain on the 16th moving him two ahead.
A good two-putt on the par three 17th then brought a fist-pumping celebration of relief from Stone and when Bezuidenhout failed to follow him in, his chance was gone.
The rookie was in tears on the 18th green after putting his third shot close as he watched Bezuidenhout claim a birdie and, when he rolled in his own par, it was only a matter of waiting for Brooks to finish.
The Englishman bogeyed the 18th to drop to 11 under, two shots clear of the South African quartet of Retief Goosen, Branden Grace, Keith Horne and Justin Walters.
Another South African, Trevor Fisher Jnr, was then at eight under alongside American Daniel Im who fired the round of the day with a 65.
|3||SMITH, Jordan L||ENG||18||-17|
|T5||FISHER JNR, Trevor||RSA||18||-14|