Rapper and songwriter Costa Tsobanoglou, popularly known as Costa Titch, collapsed and died at a music festival in Johannesburg over the weekend.
Diamond told Wasafi TV the icon was his close friend who respected him.
"He really rooted for me. He was so disciplined. When I see an indisciplined person, I just block them because I know I have surpassed you in wealth, fame and literally just everything," he said.
"But for him, he was so good. He was family to me. He was so real. When I would go to South Africa, he was even asking if he can bring a studio set up to my home."
Diamond said he had spoken to Titch a couple of days before his death.
"I just spoke to him a couple of days ago. His death was shocking to me and to think that he was young, about 27 years."
He added that he spoke to Akon about Titch's work.
"I spoke to Akon about Costa Titch, his hardworking spirit, people loved him."
Diamond has since changed his profile photo to Costa Titch's face.
In a statement to the public, the family said they've been robbed of a son and grandson.
"Death has tragically knocked at our door," it said.
"Robbing us of our beloved son, brother and grandson, Constantinos Tsobanoglou, 28, who South Africa had come to love and idolise under his stage name 'Costa Titch'.
"It is with deep pain that we find ourselves having to acknowledge his passing at this time. We are thankful for the emergency responders and all those present in his last hours on this earth."
The family also asked fans for space during this difficult time.
"As a family, we are faced with a difficult time as we try to make sense of what has befallen us and ask that we be afforded the time and space to gather ourselves.
"The Tsobanoglou family thanks you for the love and support you have given to our son, and may you continue to uplift him even in spirit. Please keep us in your prayers and uplifted in the Lord."
