Used to be, whenever the words "Rihanna" and "mature" were used in the same sentence, the latter was followed by "audiences only," and folks were attempting to decode what she meant by "Birthday Cake." Yes, for the past few years, Rih Rih has seemingly delighted in pushing both boundaries and buttons, tweaking parental units with a string of hits that were as gleefully raunchy as they were, well, unsubtle.

And while she's still the same girl in her personal life — at least if her Instagram account is to be believed — it appears that, musically, Rihanna may be in the midst of some grand metamorphosis: based on brand-new single "Diamonds," one can gather that perhaps, at long last, she's growing up.

To be fair, the single's artwork does feature her rolling diamonds into a joint, but on the song itself, she displays a marked level of (dare I say it?) maturity, one evident in the restrained production and perhaps best exemplified by the first mantra she lays on us: "I choose to be happy."

Now, at 24, she appears willing to put past relationship drama behind her (unless she decides to put Chris Brown on the "Diamonds" remix) and embrace the positivity and fulfillment of a fully realized partnership, singing "When you hold me, I'm alive" and admitting "I knew that we'd become one right away." And she does it with a remarkably clear head, in stark contrast to her previous work, like, say the druggy "We Found Love," or the whirling "Where Have You Been," both of which seemed to celebrate bad love in all its forms. This time out, she's getting by on the hope and promise of better days ahead.

You'd think, as a result, the song would be somewhat boring, at least in the canon of Rihanna's other super-charged, super-sexualized hits, but you'd be wrong. Working with an accomplished songwriter like Sia, and in the capable hands of producers Stargate and Benny Blanco, "Diamonds" instead delivers its thrills gradually, unspooling on somber synth chords and a simple backbeat, eventually building to a sumptuous chorus. There's a certain level of complexity to it, and Rihanna's voice, un-lacquered and free of studio swath, sounds warm, personable and above all sincere. She believes what she's singing here, which is a big step given the context of her words.

And sure, we don't know what the rest of her upcoming seventh album will sound like, and it's entirely possible she'll drop a raunch-tastic music video to accompany "Diamonds," though I sort of doubt it. Rihanna seems to be embracing her newfound maturity this time out, which, while probably inevitable, is also a welcome departure. She's no longer searching for love "in a hopeless place," she's found it right in front of her, and for the moment at least, she's content to stay here.

Do you like the sound of Rihanna's new single? Leave us your opinion of "Diamonds" in the comments!