I'm not sure what you mean by being named. Like La Peregrina? Or named by type?
Just to clarify - natural blister pearls should be cleaned out from the back and filled or they may break with an impact. Cultured blister pearls have a firm insert that can stay in place. Cultured mabes are the same with the insert removed and replaced with resin and backed with MOP.
Although a pendant isn't likely to face a sharp impact, it can happen. If the natural blisters formed over gasseous or spongy matter, they may be hollow, or partially hollow and it's possible that they are very thin at the top.
Does that help, or am I telling you what you already know?
Cheers,
Blaire