Miley Cyrus and Liam Hemsworth aren't planning a trip down the aisle just yet.

The Hannah Montana actress, 19, sparked engagement speculation when she flaunted a left-hand bauble at Muhammad Ali's Celebrity Fight Night XIII event in Phoenix March 24. But a source close to Cyrus told Us Weekly last Sunday that the diamond is not an engagement ring, and that her beau of three years hasn't popped the question. "I've worn this same ring on this finger since November!" the pop star later tweeted.

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Cyrus hardly needs a rock to solidify her romance with Hemsworth, 22--and a source says the singer is eager to spend as much time as she can with her man.

"His schedule is crazy right now," the source says of the Hunger Games hunk, "so she's trying to be flexible." Hemsworth tells Us he appreciates the effort: "She's very supportive!"

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Aside from a brief split in August 2010, Hemsworth and Cyrus have been dating since 2009--the duo met as costars on the set of the Nicholas Sparks tearjerker, The Last Song. "[They] are really in love," the source says.

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