Sia & 'Diamonds': Listen To Pop Star Sing The Song She Wrote For Rihanna (VIDEO)

"Diamonds" is currently the No. 1 song on the Billboard Hot 100 and has helped propel "Unapologetic," Rihanna's seventh album to the top of the Hot 200 albums chart. But here's a (widely known) secret: Rihanna didn't write it.

The track was written by Australian singer-songwriter Sia, perhaps best known to American audiences for her work with David Guetta (she's the soaring voice on "Titanium"). She performed "Diamonds" at the Norweigan-American Achievement Award ceremony on Wednesday night.

Benny Blanco, who co-produced the track with Stargate, told The Huffington Post how it all came together:

We're sitting there trying to make records, and we finally just said, "Let's just do something we like. Let's make a hip-hop record with some really cool chords on it." It didn't sound Rihanna at all. We were more thinking of making a record that sounds like Kanye. Let's make a record with a dope beat. So we did. Then Sia heard the track and instantly gravitated towards it. We weren't even thinking of putting a pop song on it, but she wrote this amazing song, and it just happened overnight. I'm still waiting for the day where they're like, "Just kidding! This is a dream, your shift starts at Taco Bell soon." Every time I hear it, I'm just like "Oh my god, this song actually happened." You never know.

"Diamonds" was the only single Def Jam dropped in advance of the album's release. Kanye West also remixed the track.

Sia's version, available above, sounds quite a bit different (mostly because it's lacking Rihanna's Barbadian accent). Let us know what you think in the comments. Other tracks produced by Blanco are available below.