Kim Kardashian faces backlash from fashion historians and Marilyn Monroe fans after donning the star’s iconic Happy Birthday dress for the 2022 Met Gala.

Kardashian stole the show at Tuesday’s glam-packed gala, arriving in the Hollywood luminary’s bedazzled frock by designer Jean-Louis — worth almost $7 million.

However, fashion experts say the delicate dress should never have been worn, labelling Kardashian’s decision as “irresponsible and unnecessary”.

Kardashian marched up the Met Gala red carpet in the same sheer nude-coloured gown that Monroe wore to sing Happy Birthday to then US president John F Kennedy in 1962.

Given its fragile nature and historical value, she wore it only for the red carpet show-stopper before changing into a replica for the rest of the night. She told Vogue she “would never want to sit in it or eat in it or have any risk of any damage” to the real thing.

It was the first time the “evocative piece of fashion history” – which is adorned with more than 6,000 hand-sewn crystals – had been worn since Monroe’s own historic outing.

But Dr Justine De Young, a professor of fashion at the Fashion Institute of Technology in the US, told People magazine Kardashian should have worn the replica from the start.

“Such an iconic piece of American history should not be put at risk of damage just for an ego-boost and photo-op,” Dr De Young said.

The 41-year-old reality TV star was given permission to wear the dress by Ripley’s Believe It or Not – the museum bought the iconic dress at auction in 2016 for US$4.8 million ($6.8 million). It has been on display there since.

Kardashian also transformed her dark locks into a bright platinum blonde to best match the icon and the gala’s 2022 theme, In America: An Anthology of Fashion.

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She also underwent another transformation, shedding more than seven kilograms to squeeze into the dress – after initially trying on a replica for size.

“When it didn’t fit me I wanted to cry because it can’t be altered at all,” Kardashian said.

“I would wear a sauna suit twice a day, run on the treadmill, completely cut out all sugar and all carbs, and just eat the cleanest vegies and protein,” she told Vogue.

“I didn’t starve myself, but I was so strict.”

Dr De Young said those remarks were also worrying.

“Crash-dieting to fit into the original dress is also an unfortunate message to be sending one more in keeping with ideals of the 1960s than today,” she said.

Monroe fans also lambasted Kardashian’s decision to wear the original dress, criticising her going to such lengths to meet the Met Gala’s “gilded glamour” theme.

Monroe historian and collector Scott Fortner told People the late actress wanted the dress to be unique to her, as it was meticulously sculpted to her body shape. Monroe was famously sewn into the gown, ahead of her Happy Birthday moment.

“The gown worn by anyone else will not be a precise fit,” he said, adding that its fabric and seams were “logically assumed” to be stressed when worn by Kardashian.

Other fans online took offence at Kardashian’s apparent attempt to compare herself to Monroe, saying the famous dress was made specifically to be worn only by the icon.

“She looks incredible, but this still feels wrong. Marilyn was exploited in life and continues to be in death, this was hers, it was made for her, she had to be sewn into it. Why can’t we let a woman who never really had anything of her own, just have this one thing?” one wrote.