~~~ placement of serial numbers (at least on the two you illustrate). Usually, the numbers are below the central graphic; monogram... but in this case it looks as though the engraver needed to search for space which kind of suggests the serial numbers might have been added later on.

In the past I've seen French pearls make their way to South America for a new home and serial numbers added on to them at that time.

In any event, the pieces certainly are pretty.

If other readers have examples of pearls with serial numbers not at the bottom/top, I ask that you please show them.