The primary reason for the painting's popularity through the years was due to the belief that it was painted by the Dutch painter Rembrandt van Rijn; a prolific respected painter believed to be one the greatest in the history of the craft and credited for developing many of its more recent genres.
For many years, the public believed it to be a genuine Rembrandt due to the fact that many believed that it was painted in the typical manner of Rembrandt which involved contrasting light and dark. It was only until the late 20th century that it was revealed that 'The Man with the Golden Helmet' was actually not his work.
Speculation that 'The Man with the Golden Helmet' wasn't actually an original work of Rembrandt had been going on for many years with many pundits and keen observers pointing to the numerous paintings originally thought to be his only for their authenticity to be revoked later on. They also pointed to important details within the painting that did not match the well-known style of its purported creator.
There was also a big fuss made about the signature made on the paintings with claims being made that they were not consistent with Rembrandt's true recognized signatures. A good number even resorted to believing that the painting might have been distorted or altered during the restoration process. All that was eventually put to rest after scientific tests were done which confirmed that it actually wasn't a Rembrandt.
The question of the authorship of the painting is one too hard to resolve. The many attempts to find out who its painter was have only gone so far as to point out that he was one of Rembrandt's contemporaries; an answer that is hardly satisfying.
The primary problem that made this search for truth all the more difficult was the Rembrandt habit of signing paintings that weren't his. This included paintings from his students that all cumulatively added up to over 700. It was finally determined that the painting would be showcased while being credited to an unknown author.
Despite being a beautiful authentic painting, its popularity was largely if not completely due its connection to Rembrandt. Following the revelation, there was a general expectation that the painting's value would eventually take a hit; an almost assured inevitability. It however, still retains the same qualities that made it a much loved work of art.
Throughout its history, we have heard various speculations about the whereabouts of the painting Man with the Helmet, but all these just stresses on its value and the quality it still holds.