The statue of the former Princess of Wales was unveiled by her sons, the Duke of Cambridge and Duke of Sussex, at her former home of Kensington Palace on what would have been her 60th birthday.
The work was created by the artist Ian Rank-Broadley, and the process of turning it into a bronze statue was carried out by Castle Fine Arts Foundry, which has its head office in Llanrhaeadr.
The firm's director, Chris Jones, said it had been an honour to complete the work, and he paid tribute to staff across its Llanrhaeadr, Stroud, and Liverpool sites for their efforts to cast Mr Rank-Broadley's work into the statue which has now been revealed to the world.
The bronze statue depicts the princess surrounded by three children to represent the "universality and generational impact" of her work.
Her short cropped hair, style of dress and portrait are based on the final period of her life – following her split from the Prince of Wales.
Kensington Palace said Diana had "gained confidence in her role as an ambassador for humanitarian causes" and that the statue "aims to convey her character and compassion".
Mr Jones explained that the firm has worked with Mr Rank-Broadley for many years, including on his memorial for the National Memorial Arboretum in Lichfield.
He said the statue had been created using a 'lost wax process' and that everyone at the company had been proud to be involved in such a landmark project.
He said: "There are so many incredible artisans we have working here and it is easy to become blase, we create so much work, from the Beatles, famous footballers, private commissions, that go round the world, but it is one of those times that you stop and take stock of the amazing things people at the company contribute.
"It will be there for hundreds of years, longer than that, and it is something we are very proud of. Everyone is."
The foundry was set up in 1990 by Chris Butler. It began in the grounds of Chirk Castle, from where it takes its name.
Mr Jones said Mr Rank-Broadley, had produced a wonderful piece of art.
He said: "It is a stunning piece of work and Ian is such an amazing portrait artist."
The sculpture would normally have taken around four to five months to complete but due to the impact of the pandemic the process took the foundry around 12 months.
The statue shows Diana wearing a sleek open-necked blouse, a wide belt and a pencil skirt.
Her hands are gently placed on the shoulders of two of the children - a boy and a girl, with the girl holding the princess's hand.
The monument is 1.25x life size and is finished with a patina of a bluish green over black.
The cast is hollow and is supported by a stainless-steel armature.
Beneath the statue is a plinth engraved with the princess' name and the date of the unveiling.
In front of the statue is a paving stone engraved with an extract inspired by The Measure of A Man poem.
It reads: "These are the units to measure the worth,
"Of this woman as a woman regardless of birth.
"Not what was her station?
"But had she a heart?
"How did she play her God-given part?"
The delayed statue, which was due to be unveiled before the end of 2017, is situated in the Sunken Garden of Kensington Palace, which was one of Diana's favourite places.
In a statement released after its unveiling the Duke of Cambridge and Duke of Sussex said: "Today, on what would have been our mother's 60th birthday, we remember her love, strength and character - qualities that made her a force for good around the world, changing countless lives for the better.
"Every day, we wish she were still with us, and our hope is that this statue will be seen forever as a symbol of her life and her legacy."
Mr Rank-Broadley said after the unveiling that he hoped the statue might provide some "solace" for the two brothers.
"I think that their mother is there in a real physical sense, perhaps in the evening when the grounds are shut they could easily come here for a moment of quiet reflection and I hope that will give them some sort of comfort or solace," he said.
He explained that William and Harry had shared poignant private moments of fun and joy from their time with their late mother when they collaborated with him on the piece.
"They made a huge contribution, in many ways I could say the sculpture belongs to them as well - they helped make it," Mr Rank-Broadley said.
He added: "They described their mother and in many ways there were private moments that were related - one certainly got the feeling she was an enormous amount of fun and (loved) playing jokes."