When I moved house in 1994 a filing cabinet draw labelled 'wire' moved with me, yes I do dip into it every so often and add/subtract. Knowing it contains a very random selection of 'stuff' I looked to see if anything would suit you. In a variety of combinations of conductor quantity/colour there were sheathes in; black, brown, red, yellow, orange, green, blue, grey, white, pink, gold.
However as there are a number of bits of 30++ year old rubber which has... let's just say deteriorated including the blue which I believe came off of a neighbours vacuum cleaner pre 1983.
Thanks to this thread almost the entire contents of the drawer and 2 others went to the scrap yard this morning, along with other 'stuff' I'm sorting and clearing.