The album sold just under 100,000 copies to become her third chart-topper in three years, and her fourth number one overall. She equals Madonna, Norah Jones and Eva Cassidy's record of most consecutive number one albums for a female artist.
One Direction drop one place from last week's number one to two with Take Me Home.
Little Mix's debut album DNA is new at three, while Led Zeppelin's live compilation Celebration Day lands at four.
A repackaged edition of Michael Bublé's former number one Christmas enters at five.
Susan Boyle - who, like Rihanna, has topped the UK album charts three times in three years - has a new entry at seven with her latest collection Standing Ovation - The Greatest Songs from the Stage.
Example's third album The Evolution of Man lands at 13. AC/DC follow their singles success this week by entering at 14 with Live at River Plate.
Whitney Houston's 'best of' compilation I Will Always Love You lands at 29.
Watch the video for Rihanna's 'Diamonds' below:
Source: Official Charts Company
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