The King is recycling a chair used by King George VI for the Coronation, in an effort to make the event more sustainable.
After he is crowned, King Charles III will move to a throne chair used during his grandfather's coronation in 1937.
It has been re-upholstered, but still features the original embroidered coats of arms on the front and back.
Camilla, the Queen Consort, has an identical chair, used by the Queen Mother during the 1937 coronation.
However, the Queen Mother's coats of arms have been replaced by newly embroidered versions created by the Royal School of Needlework (RSN).
The King wanted to reuse things where possible for the Coronation, explained Caroline de Guitaut, deputy surveyor of the King's Works of Art at the Royal Collection Trust.
"So it's giving the chairs, I suppose, a new life in a slightly different guise, but at the same time respecting that they are historic objects, and conserving them for the future," she said.
As is tradition, on 6 May, a succession of chairs will be used by the King. He will move from a chair of estate to the ancient coronation chair to be crowned, before moving to the throne chair for the moment of enthronement.
The Queen Consort will be crowned in a chair of estate before sitting in a throne chair.
The chairs of estate, which have also been re-upholstered, were originally made for the late Queen Elizabeth II and the Duke of Edinburgh for the late monarch's coronation in 1953.
The cyphers have been replaced by those of King Charles and Camilla and embroidered by the RSN.
The RSN, which celebrated its 150th anniversary last year, has been used in five successive coronations, including Edward VII's crowning.
It took two months to renovate the throne chairs, during which a family-run firm of upholsterers stripped them before building them back up with layers of wool and using red and gold braid and fringes for decoration.
Ian Block, from AT Cronin Workshop, said traditional methods were used in the work, adding: "There's 100 years of life in these."
There will also be 100 congregation chairs in Westminster Abbey, made from sustainable British oak and covered in blue velvet with the King and Queen Consort's cyphers.
These will be sold after Saturday's ceremony and the proceeds donated to charity.
Another change in tradition is the public's pledge of allegiance to the King and his heirs where people watching the Coronation will be invited to join a "chorus of millions" in the first Homage of the People.
It replaces the traditional Homage of Peers in which a long line of hereditary peers knelt and made a pledge to the monarch in person.
However, this has been described as "offensive, tone deaf and a gesture that holds the people in contempt" by a campaign group.
Republic, which wants the monarchy abolished and replaced with a directly elected head of state, says that in a democracy the head of state "should be swearing allegiance to the people, not the other way around".
"This kind of nonsense should have died with Elizabeth I, not outlived Elizabeth II," said Republic spokesman Graham Smith.
A Lambeth Palace spokesman said the homage was "very much an invitation rather than an expectation or request", adding that people could join in if it feels right, as they would for a national anthem.
In a further nod to sustainability and the King's love of nature, primary school children will be sent wildflower seeds to mark the Coronation.
More than 200,000 seed packets will be sent to state-funded primary schools, under the scheme run by the Eden Project and the Department of Education.
If planted together the project would create about 40 rugby pitch-sized wildflower meadows, the government said.
Dan James from the Eden Project said it was a fantastic opportunity for "the next generation to see the impact that wildflowers can have, even in small spaces".