A Marilyn Monroe collector has claimed that “permanent damage” has been inflicted by Kim Kardashian on the iconic dress Monroe wore to serenade John F Kennedy on his 45th birthday, shortly before the actor’s death.

Kardashian wore the gown to the Met Gala last month; photographs taken in the last week by Scott Fortner, a collector who works to authenticate and verify Monroe memorabilia, appeared to show stretched and buckled fabric and missing crystals on the back of the dress.

In the photos, posted to Instagram on Monday, rips, stretches and substantial wear and tear can be see on the dress, which also does seem to be missing some crystals with others “left hanging by a thread”.

The post quotes the dress’s owner, Ripley’s Believe It Or Not!, who at the time claimed “great care was taken to preserve this piece of pop culture history. With input from garment conservationists, appraisers, and archivists, the garment’s condition was top priority … no alterations were to be made to the dress and Kim even changed into a replica after the red carpet!⁠”

Kardashian donned the $4.8m crystal-covered nude silk gown to walk down the red carpet at the event in early May. She accessorised the garment with a white fur stole as she was unable to do the zipper up at the back.

During a fitting more than a month before the gala, Kardashian realised her assumption that the gown would slip on was optimistic. “When it didn’t fit me I wanted to cry because it can’t be altered at all,” she said.

She then undertook an extreme weight-loss regime to try and squeeze into the dress, which involved a vegetable-centric diet, lots of time on the treadmill and wearing a sauna suit twice a day. “It was such a challenge,” she said. “It was like a role, I was determined to fit it.”

Kardashian’s programme met with criticism from healthcare professionals, while her apparently insatiable desire to wear a dead woman’s dress also went down badly.

The International Council of Museums commented that “historic garments should not be worn by anybody, public or private figures”. While the dress was the property of a private collector its heritage, they continued, “must be understood as belonging to humanity” and the artefact “kept preserved for future generations”.

The dress has been kept in a temperature-controlled environment since the tourist attraction bought it in 2016. It had not been worn by anyone between Monroe and Kardashian.

Ahead of her appearance, Kardashian defended her sartorial decision. “I’m extremely respectful to the dress and what it means to American history,” she said. “I would never want to sit in it or eat in it or have any risk of any damage to it, and I won’t be wearing the kind of body makeup I usually do.”