Double denim has long been considered a bit of a fashion faux pas. As styles go, it's been sneerily described as a Canadian Tuxedo, as if people living in the Canadian outback have delusions along the lines that combining a denim jacket with denim jeans is fancy going-out gear.
And yet celebrities have been paying no heed. In fact, while some fashion commentators have been waiting for double denim to disappear, it just keeps being worn by our most popular stars of just about all ages.
So what are the rules for wearing blue-on-blue if you want to follow in Rihanna and Rita Ora's footsteps? For starters, avoid looking like you just threw on whatever you had lying around, and iron your denim jeans and shirt before putting them on.
Wear different shades of denim to break up the overall denim-ness of your outfit. Kylie barely follows this rule, as our picture shows, and yet being petite, she presents as a little line of same-coloured denim as opposed to a long streak of it.
If you want to look casual yet hip, then don your shades. A pair of big sunnies can take any double-denim outfit from looking like clashing denim to instant cool.
When it comes to accessories, don't go overboard. Less is best, and settle for one knockout piece like a big necklace or look-at-me bag.
Maybe wear a belt if you're a little on the weighty side. This breaks up your top half and bottom half, and gives you a defined waist. Why not try layering a denim jacket over a denim shirt for something a little bit different?
An interesting way to work the denim-on-denim look is to embrace the recent trend of patchwork denim. A light denim shirt with dark patch pockets is a different way to work the look. Miranda Kerr doubles up by wearing multi-coloured denim shorts with a plain denim shirt.
Just don't go doing triple denim – a denim jacket over denim shirt over jeans. A little restraint goes a long way with this look.