Hi,
I have been looking at quite a few diamonds on the JamesAllen site and am considering to get one of their diamonds. In all honesty based on looking at the 40x videos I can't tell the difference between I, J and K. Will it be like this if i see the diamonds in person?
No, you will see the difference in person. I color is borderline and only in the lower color I's will you see the tint usually, except when you put it next to a D color stone or something! I can easily see tint in J and it will not be as bright as a whiter stone. I wouldn't consider K for an engagement ring. My personal preference is G-H color, but I recommend I color for the value when greater size is wanted. J can be a very good value for those who are not color sensitive at all and it will look pretty nice face up in ideal cut stones.