Labelling ponies

[High Flutter]

I have my ponies currently in boxes, and I've started to sort them. I select a color of yarn to use, make a list and note any/all issues, then take photos of the pony and loosely tie the yarn around the pony's neck. So far, I've done white, gray and purple. n__n

Then they go back into the box, in a more organized fashion.

THIS ^^ above.

Non-volatile cotton or similar thread?   CHECK.
Visually unobtrusive?   CHECK.
Colour coding capable therefore adaptable to referencing system?   CHECK.

If anyone can find a problem with coloured yarn or cotton, (aside from the obvious colour runs in the wash - remove from pony in that case), then I salute you because this is the best darn solution so far.

I wonder if hoof bangles could become a fashionable accessory..... hmm... it could also serve as ownership. ie - "these are MY ponies, don't get them confused with your kids own toys when they play with them  "

As I kid I used to "permanently" borrow library books from school. I NEVER intentionally kept them, and when found (sometimes years later) they made their way back. Well most of them 
Point is, is that the ones which DIDN'T have an obvious library stamp or other identifiable trait (dust cover, etc...) were the ones which stayed with me, because it was too easy to "forget" they weren't mine.

Tags would get in the way, but the right thickness of "yarn bangles" around the leg would serve as a reference for myself and an ID for others - young'uns couldn't take my beautiful Italian Glory home unless someone actually wants to steal.

I do love my ponies & I do care for them, but they don't always live on the shelf.