there is a big difference between the $$$ and quality of a colour F and colour K.
if you want a diamond as big as 1C ,you need to learn more about the 4C's of a diamond.this is just the beginning...i don't want to give to too much of a lesson in here.
however, just looking at you said a colour K stone? i have to say the colour is not so good. has the stone already been set on a ring yet? if it is, is it on a 18K gold or white gold?(perhaps platinum? but i honestly doubt it!)
if you are interested in more, you can pm me as there is too much to talk about choosing a diamond.