Rough and Ready, now what

[Silveystone]

I have a rough and ready. It has been seen by two jewelers and one GIA. GIA says it is "scary big" and that I should visit a lab directly and have it seen. During his inspection the tester rang positive when measured around edges but did not register when reading through the center. He explained that this might be because of the thickness of the stone. Questions; should it be seen by another GIA prior to making a trip to the lab or should I just make the trip? After going to the lab and if it tests positive, what next?