*NOTE: This product is now called the Tone Correcting Powder.
This is a review on another of E.L.F.'s $3 Studio products. It has the same packaging as the bronzers, sturdy, has a good weight to it, and has a large mirror inside.
The idea behind this product is that by swirling your brush into the four colour correctors (shown below), you will be able to slightly mask any colour imperfections on your face. For example, the green colour would tone down any redness on your face because green neutralizes red. Additionally, you could use a concealer brush and pick up a tiny amount of the colour corrector you need and direct apply it to that spot like you would a concealer.
I sometimes like to use this as a finishing powder, just to cover up anything that my foundation hasn't already. I didn't swatch it because the colours appear white when photographed, though in person you can see the slight colour it has to it. Because of this, applying it as a last step may make you look pale, so it might be best to use as your last powder step before blush and bronzer.
The difference it makes to covering up discolouration in skin is very subtle. That doesn't mean that it isn't working correctly though. You'll notice a difference when you apply one of the colours directly to a colour imperfection on your skin.
Here's a website that teaches you how to use colour correctors: http://yourpersonalmakeupartist.com/how-apply-color-corrector
I think this product is great for it's price (like most other E.L.F. products), but if you're looking for something heavy-duty, you'd be better off using a cream colour corrector, like the one Coastal Scents offers.
Product: E.L.F.'s Correction Perfection Face Powder
Price: $3 (www.eyeslipsface.com)