Discuss AshleyBrown's answer to: What is the difference between a GIA diamond certificate and an EGL diamond certificate?

 if the GIA would grade a diamond an “I” colour and “SI2? clarity, receiving an “H” color and “SI1” clarity would be consider two upgrades (one color + one clarity).  But if that same diamond received a “G” color and “SI1” clarity, it would be considered three upgrades (two color + one clarity).

Therefore EGL graded diamonds sell at a significant discount when compared to diamonds of equivalent grades certified by the GIA.