Rihanna has long been hounded by rumors that she is a member of a shadowy organization known as the Illuminati, and on Sunday those mumblings started once again, as she flashed a hand signal at the 2013 American Music Awards (AMAs) that many people associate with the group.

Rihanna made headlines by winning the 2013 award for Best R&B Artist at Sunday's AMAs, but she also attracted attention for the hand symbol, which has reignited a simmering controversy over who really controls the music industry.

By shaping her hands into a diamond shape, she followed in a tradition of potential Illuminati repping most often associated with rapper Jay Z, but which has found its way into other artists' stage shows for some time. Click here to see a Twitter user's photo of Rihanna flashing a diamond hand signal Sunday night. Katy Perry, Taylor Swift, Beyoncé, Lady Gaga and many other popular artists have also been accused of being members of the Illuminati, but now Rihanna is back in the headlines after flashing the diamond symbol during her AMA performance of "Diamonds (in the Sky)."

References to the Illuminati's influence on pop music generally allege that a secretive group has control over the music industry, and that artists are accepted into the group in exchange for doing certain deeds or following certain requirements of a group of powerful, unnamed figures who run the world from behind the scenes. Illuminati rumors often go hand-in-hand with accusations that people are part of a New World Order-style scheme or that they are practicing Freemasons or Satanists or members of the occult.

Many viewers of this years AMAs took to Twitter immediately following Rihanna's performance to post photos that they believe show that she is giving a shout-out to the Illuminati. In addition to the diamond signal, one user found that a triangle shape made by her left arm and body is another more subtle Illuminati hat-tip. Click here to see a Twitter user's photo of that moment.

Twitter feeds were inundated by tweets by users calling Rihanna out for her supposed Illuminati-repping.

"Rihanna throwin up the illuminati i see u girl," tweeted @xobeckyyy.

"RIHANNA JUST FLASHED THE ILLUMINATI SYMBOL WHEN SHE SAID 'universe' IN HER PERFORMANCE. You heard it first from me," tweeted @WEFortenberry.

The world may never know whether there really is an Illuminati or if Rihanna is a member of it, but one thing is for sure: there are many people who believe both things to be true.