Joni Mitchell turns 70 this November. But as she proved before adoring fans to kickoff this year's Luminato festival - where she was listed on the billboard outside the entrance simply as 'Joni' - she is still a formidable presence with an undiminished aura all her own.

The singer songwriter has a Prairie openness in her fierce blue gaze and Nordic cheekbones so pronounced one could imagine them cut into a rock face. While never known as a style guru others followed for her look alone, Joni personified different notions of the rock goddess over her long career. From long-haired hippie songstress in flowing Boho maxis to a Lady of the Canyon in vintage satin, Mitchell has dabbled with style over the years in the same artistic, exploratory way she experimented with genres in her painting and her music.

The artists who performed at the recent Luminato tribute seemed to encompass the varied aspects of Joni's persona and prodigious output. Rufus Wainwright played Joni the diva, reimagining classics like "All I Want" as a Vegas-style lounge ditty. Fellow singer/songwriter Glen Hansard's depth of feeling and respect for folk tradition made him the perfect choice for Joni as Troubadour. Vocal stylist Kathleen Edwards was Joni as the wacked-out, wide-eyed country gal. Poised and appearing on stage barefoot, Lizz Wright revealed the side of Joni that's a gifted experimental jazz artist. Having spent a lifetime defying stereotypes and flaunting convention, Joni is particularly hard to pin down at 70. A diva, a truth teller, a poet and an iconoclast who is herself an icon, the secret to her impossible-to-bottle essence seems to lie in her singular fearlessness.

Despite having been, in her words, "kind of out of it" for the past 10 years thanks to a grab-bag of health issues that saw her retreat from the public gaze, Joni marched on to the stage with the ease of one who has spent a lifetime in the spotlight. Dressed in a fantastic avant-garde nun's habit of dove grey with peaked shoulders, patched pockets and a full skirt, like the uniform of a high priestess from another, more tasteful planet, Joni had her long platinum locks piled on top of her head in the stylized pompadour of a Spanish queen under the influence of Elvis.

So strong was her physical appearance and almost regal bearing that it hardly seemed surprising when she started to move and weave to the music like a girl, even though we had been told it was unlikely Joni would attend this celebration, let alone perform. She started by rhythmically speaking the words of a poem she had recently written based on the diary of painter Emily Carr, another lonely and wild female Canadian artist. Moving and sweeping to the beat, she intoned with a voice rubbed raw from years of chain smoking, which gave her words depth and gravitas. (Perhaps what this hard-to-categorize virtuoso has always been is an artist of the spoken word?)

As soon as it became clear to everyone in the room that she still had more swagger on that stage than the band and the roster of gifted young performers together - and that she was enjoying herself immensely - Joni surprised us all by starting to sing.

No, it wasn't the same lilting, crystalline voice that made us all play "Blue," over and over again in our teenage bedrooms until the scratches on the vinyl became part of the song in your head. It was something more unusual: the voice of a great artist who knows how to make magic with what she's got.

In her youth and ours, we looked to Joni for guidance as to how to be cool, and still be a woman. It was brave to set out from Saskatchewan with a guitar and little else. It was even more fearless to peel your skin like an onion and reveal your innermost self to others in song.

As a young woman, Joni's fearlessness taught us to stare down those who didn't get what you were trying to say or who you were trying to be and keep on writing, painting and singing - no matter what. Now we can look to her with the same admiration for taking her fearlessness to the next level. After all, if style is conviction, Joni has always had it in spades.

Karen von Hahn is a Toronto-based writer, trend observer and style commentator. Contact her at kvh@karenvonhahn.com.