The journey began in 1964 when Montrealer Lisa Carducci was 21 years old and a newlywed.
On her honeymoon in Pompeii, Italy, she came across a mask sitting in the grass while she was touring an amphitheatre that dates back to 80 BC.
Pompeii is known for its stunning collection of artifacts after Mt. Vesuvius erupted in 79 AD and buried residents and architecture in ash, largely intact.
"I spontaneously took [the mask] and put it in my purse," Carducci told CBC's Daybreak.
"I never had the feeling I was taking something, just taking a souvenir of my ancestor's land."
Carducci says the terracotta mask easily fit in her hand and weighed about 300g.
Embarrassed, she says she only later showed the mask to her new husband who said he didn't want to hear about it.
Long trip home
Carducci says she realized she had to return the mask while living in China in the 1990s.
She saw how wealthy Chinese were buying stolen artifacts to repatriate them, and it reminded her of the Pompeii mask.
In 2001, she returned the mask to ruins in Pompeii.
But she says nobody was able to refer her to the proper authorities, so she hung on to the artifact.
In 2007, a friend working at the Italian embassy in Beijing gave her the e-mail address within the heritage ministry.
After about three months of correspondence, she was told someone would get in touch with her.
Carducci says that never happened.
One more try
Carducci's recent effort to return the mask was successful.
She returned to Pompeii in October and hand-delivered it to an Italian official.
Carducci says she was expecting to be punished.
"But [the official] was very kind with me. He said, 'What you did 50 years ago was not so nice, but what you are doing today is much better.'"
Carducci says she finally feels at peace, and she encourages other travellers to leave artifacts in their place.