A picture tweeted by Cyrus -- designed to show off her new manicure -- showed what appeared to be a large diamond engagement ring on her newly manicured hand. It was accompanied by a message promoting a brand of nail polish.
A source close to Cyrus told Us Weekly that the ring is not an engagement ring and Cyrus is happy just dating Hemsworth.
Hemsworth, 22, and Cyrus, 19, have been dating since meeting on the set of their 2009 film "The Last Song."
Until recently, the Aussie had been known mostly for his relationship with the "Hannah Montana" starlet and as the younger brother of actor, Chris Hemsworth -- who starred in "Thor."
But the younger Hemsworth's star is on the rise thanks to a leading role in the blockbuster film "The Hunger Games," which had the third-biggest opening ever this weekend, raking in an estimated $155 million.
The loved-up pair last appeared in public together for the US premiere of "The Hunger Games" where, when asked what the biggest challenge for Liam was while filming the drama movie, Cyrus said, "I think the hardest part for Liam was being away from me."
A source also told OK! magazine that the pair have seriously discussed getting married.
"They're still keeping it a big secret, but they're seriously talking marriage. Liam is crazy about her! Miley wants the whole nine yards as far as a big wedding goes," the source said.