Bailey Gwynne died from a wound to the heart inflicted during a fight at Cults Academy in Aberdeen on 28 October last year.
On Monday, a teenager, who cannot be named for legal reasons, was convicted of his culpable homicide following a trial at the High Court in the city.
Last night, Kate Gwynne issued a statement in which she said: “We will always be immensely proud that Bailey is our son.
“It has always been a true blessing and a privilege to have Bailey, and to share the honour of knowing, raising and loving him. That is not something that time or our parting will ever change.”
Bailey was a fifth-year pupil described by teachers as hard-working and well-behaved.
He had recently excelled himself in exams. The gym enthusiast lived with his parents and four young brothers.
His mother said: “Nothing will give us back what has been taken and the only thing that we truly want.
“That is something that we as a family must try to live with.”
Kate Gwynne described her son as a “true gent” who was never happier than when chilling with his friends and his dog after a visit to the gym.
The statement ended with the words: “With love we hold you in our hearts. Walk tall Bailey-Boy.”
Bailey’s family attended the five-day trial which saw the youth accused of murdering him by stabbing him once in the chest.
But the jury found him guilty of the lesser charge of culpable homicide and of two other charges of being in possession of knives and two knuckledusters at the school on occasions between 19 August 2014 and the day of the fatal attack.
He will be sentenced at the High Court in Edinburgh on 1 April.
Aberdeen City Council is to hold a review into Bailey’s death to identify any lessons that can be learned from the fatal stabbing which followed what was described as a “trivial” row.
Kate Gwynne thanked all those who provided support to the family, praising police, family liaison officers and procurator-fiscal staff involved in prosecuting her son’s killer.