The trophy of regional rugby was broken in half during celebrations after the Hawke's Bay Magpies beat Wellington 20-18 on Saturday.
Social media images showed the damaged shield with white powder and a rolled up bank note on it - suggesting drug use.
But James Dwan, who has been repairing the Ranfurly Shield over the past eight years, told RNZ's First Up the white powder will most likely be from plaster he had added a few years ago to hold the centre piece in place.
"I was having a bit of a think about that, and all of a sudden I thought 'I know what that is'. On the inside the centrepiece, the actual little oval badge in the middle of it, I actually put plaster in behind that to strengthen it a few years ago and I've got a funny feeling there's still a bit of that powder.
"That's what it'll be, if you had knocked it, the shield, it would have loosened a bit of that powder."
New Zealand Rugby has launched an investigation into the matter and the Hawke's Bay Rugby boss says he does not believe players were involved in snorting cocaine.
Dwan said the broken Ranfurly Shield would come back to him on Thursday and he would have a look at it straight away.
Over the past eight years, he had restored the old shield and the new one, fixing dents and scratches.
"Tidy up the small shields, some of them have taken a battering, remove some of the engraving. People unscrew the little shields and engrave their names in the back of them and things like that. So it's generally a tickle up every now [and then] when it gets to a point where something needs to be done."
He said the original wood of the shield and original small shield pieces were in Wellington at NZ Rugby's headquarters.
The centre section, however, has been transferred onto the new shield. Dwan said the new wood was a hard piece of English oak.
"Basically, it was a case of sourcing a nice piece of oak, which is what the original one's made of, and the object of the game was to make it as strong as we could.
"So we've gone to roughly about two-and-a-half, three times thicker than the original, and it's about forty millimetres wider and taller, which has taken it back to what it originally would have been back in day one, because over the years it's had that much taken off the woodwork."
Dwan said he was gutted when he heard about the damage over the weekend.
"I got the phone call yesterday from a neighbour and she said, 'I've just been watching the news ... I'm crying for you'.
"I said 'oh no', but I was not surprised ... I knew something was going to happen to it.
"I've seen it happen that many times now and I've seen the way that shield's been treated over the last maybe 10 years."
Dwan told First Up he would have a very close look at the damage when the shield came back to him.
"I spoke to the guy that did the work on the original one, he's a cabinet maker, and he said, 'you don't break oak like that'.
"It's a very durable timber ... it's not the sort of thing that splits, because of the weave of the grain. It has to have one hell of a knock to do that."
He said to break the shield in half, you would basically have to run over it with a truck.
"They're going to have to put something in place now to stop this happening. It should never go back to the changing room. They should do the photo shoots on the ground. Get your photo taken with a shield, pass it round the team, give it a kiss, whatever. And then it gets put on a table somewhere so everyone can look at it.
"Then of course, from there, it goes out to functions and schools and things, which is great. That's where you keep the spirit of the shield up.
"But you've got to have a guardian that takes that shield along and he's the guy that looks after it and makes sure nothing happens to it, and he takes it home and puts it under his bed or wherever the hell it's kept. But it's his job to look after it."