Okay, I know the craze over Chanel Particulière has subsided already. But I still adore this colour to bits. When I came across the Etude House BR303 on their website, I thought it might possibly be a dupe for Particulière so I purchased it.
When I received the bottle, I was rather disappointed because it does not look the same. In the bottle, BR303 has more of a grey tinge to it in comparison to Particulière. After trying it out however I was pleasantly surprised.
Middle finger: Chanel Particulière, Ring finger: Etude House BR303. I applied one coat of each (though a thicker coat for BR303).
They look pretty darn similar to me! There is a HUGE difference in opacity and viscosity, but the colour is the most important in my opinion (when it comes to Particuliere). As most reviews/swatches have pointed out, Chanel Particulière is opaque with one coat if applied well although I think two coats gives the true colour of the bottle. Particulière applies like a dream as well as drying pretty fast. Etude House BR303 on the other hand, is quite runny and so is hard to get a even spread with just one coat. I don't know if you can tell from the pictures but the BR303 kind of ran and clumped a little on the side (so in the pictures the BR303 looks warmer on the nail because there is still some pink showing through). Also BR303 is less opaque than Particulière if the same amount is applied.
With two coats of BR303, I think it would definitely be a dupe for Particulière (in terms of colour). I'd say roughly 95% similarity, a closer match than the swatches I've seen for OPI You Don’t Know Jacques.