NouveGnome-Gray icons designed for Gnome and to be use with dark themes. It looks beautiful with every theme, you can give a try.
NouveGnome-Colors looks good with light themes, Author mentioned these icons are not completed yet but you can install them.
You can use Gnome-tweak-tool or Ubuntu-Tweak to change icons. Also Checkout Icons Collection.

1: NouveGnome-Gray Icons
icons

ubuntu icons

To install NouveGnome-Gray icons in Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal:


2: NouveGnome-Color Icons
icons

linux icons

To install NouveGnome-Color icons in Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal:

You can install these icons on other distributions from here.
That's it
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