Mono for Android Color Picker sample03 Jul 2012 | Xamarin.Android Color Picker
The Project, which you can find on Github, at the moment contains two different Color Picker dialogs. A simple one, which can also be found in the Android SDK samples and a more advanced one, where hue and alpha can be picked, which was ported from Sergey Margaritov's android-ColorPickerPreference appication.
Simple round color picker from Android SDK samples.
Sergey's Color Picker without the alpha control.
Sergey's Color Picker with the alpha control
The images seem a bit banded, but on the actual device it shows up nice and smooth. This is because the screenshots were taken from the emulator.
Feel free to fork and watch my github repo with the project. Also leave a comment if you want to see other types of color pickers implemented or have questions.