I sometimes need to label socks either a) to distinguish similar socks belonging to different family members (in which case a coloured mark works fine), or b) to be able to return lost property (in which case the full name or initials needs to be present).
For plain white or light-coloured socks, I can write the name / initials on the sole of the foot or put a coloured dot there with a permanent marker.
How can I similarly label very dark-coloured or black socks where a marker doesn't show up? I do have printed name labels but sewing one of those into every sock seems like complete overkill.