The denim effect polish by Nails Inc is a fairly new product. Much like the leather effect one I reviewed a while ago, it is a textured polish that aims to look like denim. All you need is one coat of the polish and it will dry textured. You don't apply a top coat either as the matte look makes it look really denim-y. I have seen a lot of reviews that say it chips easily, and I too have had a few chippings already but this could be due to the lack of protective top coat. I however really like the look, and I really like the little denim lid that it comes in. Not only does it look good, it gives you a bit of extra grip when painting your nails! The actually textured look is achieved by small grains of glitter, so make sure to wear a base coat so you don't scratch your nails. It's not as rough as a glitter polish but just gives the variation in colour to give it the denim appearance.
You can buy the polish in a kit for £19 which comes with little star studs, so you can make your nails look like a pair of jeans. I however just had the polish, and decided to put my own twist on the look. I used a silver Model's Own nail art pen for the zip detailing.