Styles To Layers

This extension will re-layer your selected items or the whole document according to their color (stroke or fill). Each style will be put onto it's own layer. This way you can devide elements by their colors with ease. If you have empty layers after sorting with different types (strokes, then first or vice versa) you can use Remove Empty Groups to cleanup.

You can use the separate Cleanup Styles extension to migrate these separated attributes into style attribute.

This extension has possible parallels with https://wiki.evilmadscientist.com/Inkscape_and_WaterColorBot#Snap_Colors_to_Layers_.28beta.29