Some days ago I have published a free library with chart controls which can be used in client applications. The library can be used in WPF desktop applications, in Windows Store apps and in Silverlight applications.
Download the binaries, source code and some test applications: http://modernuicharts.codeplex.com/
Or directly try them in the Silverlight application: http://www.mossblogger.de/charts/
I needed Modern UI Charts for my own application which should run on Desktop (WPF), Web (Silverlight) and Windows 8 devices and I didn't want to use 3 different third party charting components. That’s why I created the charts from scratch and used them in the tool “SharePoint Code Analysis Framework (SPCAF)” (http://go.spcaf.com/VSGallery) which I have developed with Matthias Einig.
Custom Color Palette e.g. with gradients, mono chrome