Missing color picker icon in tool button

[redtide]

In line 75 of src/coloreditor.cpp:

pickerButton->setIcon(QIcon::fromTheme("color-picker"));

however, there is no (standard) color-picker theme icon, so it's not loaded.
Which icon could be used to be loaded from resource instead?

Side note: is it required for the app icon to be in the resource file if it's supposed to be installed?
I adopted a method to search in the build directory (CMAKE_CURRENT_BINARY_DIR) when running from the IDE, otherwise in the installed destination.