Apple - Is it possible to change the Finder sidebar icons
CandyBar should do the trick for you.
If you want to use the default Mavericks OS X Finder Icons, go to System/Library/CoreServices/CoreTypes.bundle (right-click > Show Package contents)/Contents/Resources
.
Get Info
on the folder in finder sidebar.- Drag the .icns file (e.g.
ToolbarDownloadsFolderIcons.icns
on to the small icon inGet Info
window to the left of Downloads.