The victim was on the train waiting at Oxford Circus station when four men grabbed the necklace as the doors were closing at around 3.55am on February 9.
There was a gold wedding ring attached to the gold chain, which has “huge sentimental value” to the victim.
Police say it had the name “Finola” and the date “2.9.89” engraved on the inside.
A 24-year-old man has been arrested on suspicion of robbery.
British Transport Police (BTP) detectives are investigating the incident and believe that the men pictured may have information that could help their investigation.
Anyone with information is asked to contact the BTP by texting 61016 or by calling 0800 40 50 40 quoting reference 446 of 10 February 2025.
Alternatively, contact Crimestoppers anonymously on 0800 555 111.
