well i have joked about using wee to age copper covered guitars before - but luckily a weak vinegar solution works just as well for that! I have heard of ageing chrome with urine - but i dont fancy that
there are lots of stories about the original fender clay dots, and a couple of different looks which suggests they may have used different things at different times before finally switching to pearl
its pretty much accepted that they used some kind of filler at some point, supported by factory workers from the time talking about a toothpaste like filler and known inconsistencies in the dots. I think they called it ivorine or something like that, which happens to be a simialr constitution to the resin used to make these poker chips
then i found this quote which adds some weight to it
"Fred Stuart, John Suhr and John English did a lot of research on this back in the early Custom Shop days. The best they could find out was that it was a material called "Harvite", that was a fine clay impregnated phenolic resin. It also used to be used in old poker chips and hotel key fobs."
i did try the callaham dots - which are similar, but a pale grey colour and they dont really change colour with the application of rosewood oils, so i guess they use a more plasticy modern resin.
with the originals you often see darker dots on the darker fretboards which suggests that they change colour from a combination of rosewood oils and playing wear - - which these harvite dotsseem to do too!
so yeah, authentic fender blue and red dots are now available ;)