The former Newcastle coach has been discussing the young shot stopper.
Indeed, many might assume an increased chance of making the senior side would benefit Darlow but Stone thinks the youngster needs to learn from what Krul does day in, day out at St James' Park.
And he is quoted as saying by the Gazette: "He needs to be around top coaches and keepers. He needs to watch what Tim Krul does every day.
"It's a real shame Tim is out for the season. He's lost the chance to watch and learn what the best do. Tim is a World Cup 'keeper for Holland and [has been] a Premier League 'keeper for five years. Karl can learn from him.
"He's young. You look at keepers who are 27 or 28 and they're still learning. He's in the right place. Newcastle give youngsters a chance. They buy cheap. With no disrespect to Forest they've come from a lower club. They'll try to get him to the next level."
Much like with Jamaal Lascelles, though, it's certainly no disaster that Darlow may need time to develop. The fact Krul is out may be a blow for most involved - but it's not for Rob Elliot.
Indeed, Newcastle have relied upon their stand-in goalkeeper heavily over the last few weeks, with Elliot pulling out the stops against Tottenham, Bournemouth and more.
Perhaps Darlow can learn just as much from him, then, as he would have from Krul.
Next up for Newcastle is a home clash against Aston Villa, where their shot stopper may not be tested as much as usual. You never know, though, especially when you're at the wrong end of the Premier League table.