text: On 5 October 2016, Ranga Dias and Isaac F. Silvera of Harvard University released claims of experimental evidence that solid metallic hydrogen had been synthesized in the laboratory at a pressure of around  using a diamond anvil cell. This manuscript was available in October 2016, and a revised version was subsequently published in the journal Science in January 2017.
  In the preprint version of the paper, Dias and Silvera write:
  Silvera stated that they did not repeat their experiment, since more tests could damage or destroy their existing sample, but assured the scientific community that more tests are coming.  He also stated that the pressure would eventually be released, in order to find out whether the sample was metastable (i.e., whether it would persist in its metallic state even after the pressure was released).
  Shortly after the claim was published in Science, Nature news division published an article stating that some other physicists regarded the result with skepticism. Prominent members of the high pressure research community criticized the claimed results, questioning the claimed pressures or the presence of metallic hydrogen at the pressures claimed.
  In February 2017, it was reported that the sample of claimed metallic hydrogen was lost, after the diamond anvils it was contained between broke.
  In August 2017, Silvera and Dias issued an erratum to the Science article, regarding corrected reflectance values due to variations between the optical density of stressed natural diamonds and the synthetic diamonds used in their pre-compression diamond anvil cell.
  In June 2019 a team at the Commissariat à l'énergie atomique et aux énergies alternatives (French Alternative Energies & Atomic Energy Commission) claimed to have created metallic hydrogen at around 425GPa using a toroidal profile diamond anvil cell produced using electron beam machining.
  W. Ferreira et al. (including Dias and Silvera) released a preprint in September 2022 claiming to have repeated the experiment, finding metallisation of hydrogen between 477 and 491 GPa. This time, the pressure was released to assess the question of metastability. They reported that metallic hydrogen was not found to be metastable to zero pressure, and that transformation to the molecular phase likely occurred between 113 and 84 GPa. The authors plan to study the metallisation and metastability of deuterium in the future.