When acclaimed author Jeffrey Archer finished an early copy of his next thriller, he thought a crucial piece was missing: how would readers think a false crown could be made to imitate the historic one worn by the late Queen Elizabeth?

Here's the story of Queen Elizabeth's famous crown replica.

Creating The Perfect Replica

Traitors Gate, his novel, depicts an ambitious raid on the Crown Jewels stored at the Tower of London. But, without giving too much away about the plot, suffice it to say that a duplicate of the Imperial State Crownwas key to the theft.

Archer resorted to a friend, jeweler Alan Gard, 87, to see whether a near likeness could be constructed. "It was quite a challenge, even for one of the greatest craftsmen on Earth," Archer, 83, exaggerates.

Even the most skilled craftsmen would struggle to create anything as stunning as the crown, which features the Cullinan II diamondas its centerpiece and is encrusted with almost 2,800 gems.

The Black Prince's Ruby rests above the Cullinan II, while the Stuart Sapphiresits on the back of the middle ring. That crown, too, was a knockoff. The Imperial State Crown, designed in 1937 for King Charles' grandfather George VI's coronation, was based on one designed for Queen Victoria in 1838.

It has been worn during two additional coronations since then (Queen Elizabeth's in 1953 and King Charles' in 2023) as well as hundreds of formal openings of Parliament.

It is one of the key draws for visitors to the Tower of London who want to see the Crown Jewels. While tourists enter through the front door, Archer creates a plot in which burglars use an audacious alternative.

The storyteller was inspired to create Traitors Gate after a conversation with a former member of the royal household who hinted at how it could be done. His early book Kane and Abel is on its 132nd publication, and his novels have been translated into 47 languages.

He then began investigating the intricate route with the assistance of a London cab driver and was nearly rumbled by wardens at the Tower when he made notes at one of the gates.

However, Archer's plea to his buddy Gard, who had created custom jewelryfor Archer's wife Dame Mary, began on Christmas Eve 2021 with a covert, hidden voicemail.

It's still on Gard's phone (and was recently played to PEOPLE) and said:

Gard took a couple of weeks to think about it and analyze whether he could effectively turn it in after the two met to discuss the idea. Gard tells PEOPLE:

Gard reveals the crown to PEOPLE at his basement studio and workshop in London's diamond district, Hatton Garden, by lifting it out of a bright red box (manufactured by the same company that supplies the palace and decorated with the late Queen Elizabeth's cypher).

It was there that the basic metal alloy frame, glass stones, cultured pearls, and synthetic stones were meticulously placed. The crown had roughly 30 individual components to build, and Gard believes it would have been quicker to work on the actual thing because he could have used a soldering iron to set in the stones.

This, however, had to be done with nuts and bolts. "It was more difficult for me to make than the real one. When you’re working with real goldand diamondsyou can put some heat on," he says.

Gard thinks that the centerpiece, a flawless 317-carat Cullinan diamond (actual value roughly $400 million), was replicated for around $300, including the purchasing of the glass, cutting, and placing it into the crown.

Gard had to drill dozens of holes to set in the tiny glass bits that would replicate the diamonds in the genuine thing for the ball that rests on top.

Because the novel is set more than two decades ago, it is the late Queen who delivers the speech at the State Opening of Parliament near the end.

Gard worked on the sculpture for about 500 hours over the course of 18 months. He had spent a few hours drilling holes for the little glass "stones" on the orb that sits atop the crown on the day Queen Elizabeth died on September 8, 2022.

The Queen detects something is wrong in the book, but being stoic and dutiful, she continues with the businessat hand and subsequently queries her aides about it in her own modest but strong manner.

The idea of conversing in his luxury apartment above the River Thames, for Archer, wasn't to trick her. It was done to keep spectators from noticing for long enough.

"I'm really convinced if she's sitting on the throne and you're where the nearest Lord is over there" — he indicates to a military drum (used in the Queen's burial) that is displayed — "you would have no idea, especially if she was wearing it. Absolutely no idea at all."

Gard, like many others, is curious whether someone could have carried off a similar crime. With a cheeky grin on his face, he asks Archer, "Do you think it could work?"