Selvedge or selvage denim (the former is the British spelling, the latter the American) is a self-finished denim where the edge (see where the spelling comes from?) ensures the fabric won’t unravel. It s usually finished in red or orange, the colour of which you can see if the jeans are rolled up – rather than an overlocked finish. Selvedge denim is made on a shuttle loom that means the resulting fabric is narrower (typically a yard wide) and is associated with premium quality. Very few factories in the world still use shuttle looms and for a while the Japanese had a near-monopoly thanks to that nation’s fascination with all things immediately post-war American (though the most famous denim mill in history was Cone Mills in Greensboro, North Carolina that produced denim for Levi Strauss) – so yes, this denim will be more expensive. While most selvedge denim tends to be raw there is no actual connection between the two terms. Raw simply means the denim has not been pre-washed – which is why if you wear white sneakers with new raw denim jeans you will seen find they have turned blue.
For the full article see: http://www.gq-magazine.co.uk/article/what-is-the-difference-between-selvedge-and-raw-denim