It is not a brand inscription that I recognize, if it were also inscribed with a lab report number, such as GIA 123456789 then you could look it up online using their report check feature. But without that information, you're probably going to have to pull the stone and start from scratch.
Talk to the seller. If they can't give you useful information, ignore the inscription and rely on your own skills or your own grader (which you should probably do anyway).