I've had this Rouge Serum for a while (in fact, since the Rouge Serums were known as Serums de Rouge!) and whilst I don't wear it very often I thought I'd review it as I don't see the Serum de Rouge line getting a lot of love online and actually I think its a pretty good formula, especially containing as it does an SPF 20. It's a very soft formula and feels lovely to apply; once on the lips it feels quite moisturising.
640 ('Soft pink') is a medium to light pink shade (on me it errs on the paler side).
I'm not sure this shade is the perfect match for me - when I'm pale it washes me out somewhat and I feel it clashes a bit with my yellow-toned skin. However I'm quite liking it at the moment having picked up a bit of colour (despite the factor 50!) on a recent holiday.
I also had this in a hot pink shade but I seem to have lost it, however I'm keen to try the peachier shades in the line as I think they'll work better with my skin and I do really like the formula. I'm not one for thicker feeling lipsticks that require care (or a lipbrush!) to apply; the fact that I can generously apply this without really needing a mirror really appeals. I'm not that fussed about the packaging - it's a bit fussy and dated, though the clicky pen is quite cool.
Serum de Rouge costs £26.