As I was never particularly active with this icon theme I will instead link to the KrystalSVG icon theme that is actively being worked on and on kde's own git infrastructure: KrystalSVG(store.kde.org)[https://store.kde.org/p/2193019] git repository: KrystalSVG(git)[https://invent.kde.org/blackcrack/krystalsvg]
An icon theme port from trinity's crystalsvg to new plasma 5 / kde 5
Copy the files to either: /usr/share/icons for usage of all users (remember to use root rights) or ~/.local/share/icons for a single user on kde systems or ~/.icons for single user on mate,gnome,cinnamon,xfce