There was an article in Yorkshire Terrier Magazine about twenty years ago stating "put a flash light into a yorkshire Terriers eyes if they reflect green you have a silk and if they reflect red you have a woolly"
That night the article arrived in subscribers mailbox, the lights thoughout the yorkie world quickly turned off and flashing lights turned on to test this theory,
Many breeders continue to believe the theory today BUT just as many say it's false.
Who knows....