I bought Sonia Kashuk Perfecting Brightening Primer whilst over in the States as I saw number of You Tubers rave about it. At that point I was suffering from a serious obsession with luminous skin and the 'lit from within' look.
Sidenote: I believe the name of this has now changed to Sonia Kashuk Perfecting Translucent Illuminator.
The packaging for this one is a little odd, it's a hard case in a tube shape with a pump on. I love pumps as it means that you get the same amount out each time.
The primer itself is of a thin consistency and the moment I smoothed it into my skin my face is transformed into a more bright, radiant complexion.
I wouldn't say it gives a ridiculous amount of brightness though so it's perfect if you wanted to look good going somewhere with limited or no foundation on at all. Generally I use this primer and then apply my foundation and it just brightens it up just a little whilst helping my make up last longer.
The bottom line is.. this is a really good primer or something that you can wear on it's own that looks virtually undetectable, just like it's your own skin.