How is the color of a diamond evaluated by GIA, EGl, etc.?

Question

Is the color judged by its appearance when looking at it from the top, side or bottom? What type of light is used? Do GIA, EGL, etc. have one or more gemologists look at each diamond?

Thanks in advance

Answer 1

From the bottom. Using a pure white light. And, no not necessarily. Color is, unfortunately, something of a subjective decision, so three different gemologists could come up with three different grades. Not usually, but it can happen. And GIA could rate a stone differently then EGL - EGL tends to be very...generous..with their ratings...