The auction house seems to be very open about the whole blister/blister pearl point and provides details about both reports/studies made on this piece by The Netherlands Lab and SSEF. That they don't agree is reflective of the opinions out in the trade on such objects. It is not clear and either of them could be right but even if The Netherlands lab is I guess the trade is going to believe the SSEF's take on it?
Wonder what the difference in price is between a blister and blister pearl with such a story behind it? Good thing it had such a provenance! If it didn't there probably would be a huge difference.