I have a question on the colors that the Scotweb tartan designer shows and their accuracy.

My wife and I are designing a family tartan and I am certain we are going to register it once we're have something we like. We are using the Scotweb design software, which I find phenomenal, but how accurate are the colors that are shown on the computer screen to what the mills will produce? From what I read the colors can vary significantly from mill to mill. Or are these colors taken from a certain mill?

Would the best way be to order a swatch of material from each mill and see what I like best? I can't imagine that it'd be cheap that way, though I'd rather spend a little more and make sure I have it right the first time.

Gerald