the blue stain on the edge of this granite is a perfect example of an inspection where asking the right questions is critical. For example, many of you suggested that CA glue accelerator was used to cause the blue stain. This would be accurate if in fact CA glue was used. In this case it was not. Your next step would be to ask step by step what occurred during the fabrication process and everything that happened afterward. In this case everything was normal except for the fact that stone stone was resined. Now if we look at the minerals contained in this stone we would see that copper is one of them. Given exposure to moisture and air the copper would begin to oxidize causing this discoloration. The reason it did not oxidize before is do to the fact that the resin was protecting the stone. When the edge was profiled, it was opened up and copper was exposed. Now there are several techniques that may possibly remove the copper staining. A poultice if iron out may work or somethings I have had luck with heat.
Keep in mind that you can also have the stone tested for copper if you need 100% proof.