22K inquires

I have some inquiries regarding 22K gold. First of all, is there any perceptible colour difference between it and 24K. If I were to hold up a highly polished piece of 22K next to a highly polished piece of 24K, would I notice a difference?

Also if I cannot find a master alloy for 22K, May I just use one designed for 18K and alloy to 22K? Thanks for any input,

ArgentumMoon