The 19-year-old, who will wed Hunger Games star Liam Hemsworth, tweeted her fans: "I feel like my dreams are coming true."
The impressive sparkler that 22-year-old Liam used to seal the deal was revealed this week.
Neil Lane jewellers, who made the 3.5-carat cushion-cut diamond ring for Liam, said they came to him wanting "something unusual… something really beautiful and romantic".
It was handcrafted in 18-karat gold with intricately carved diamond floral motifs in an art nouveau pattern.
The centre stone is a real talking point: it’s an antique dating back to the late 19th century.
“It was hand-cut around 1880 or 1890 and it’s unique and in its original form,” Neil told People.
“At that time no two diamonds were alike, as they were all hand-cut, so it’s fascinating to look at because it hasn’t been re-cut to look contemporary over the years. I find that really romantic.
"The impressive bauble, which is "a contemporary design based on vintage aesthetics" was finished just in time for Liam's May 31 proposal.
Featuring small diamonds on the hand-crafted band, it ensures that “the light flashes and sparkles no matter where Miley moves her hand”, says the jeweller.
Liam and Miley first met – and fell in love while filming The Last Song.
The Hannah Montana star has described the handsome Australian as "her first serious boyfriend" after romances with Nick Jonas and model Justin Gaston.
Miley's dad is thrilled about his daughter's intentions to wed. He posted on Twitter: "All I ever hoped for as a Daddy was to see my kids reach their dreams. To find happiness…peace of mind …and someday know… true love."