I think you're right to question this, but maybe the size of the
pearls has something to do with it, if they're very tiny. I always
string pearls on silk and knot between, the exception being very
small -to- tiny pearls ( as in creating tassels with seed pearls,
perhaps, or if the knots would appear clunky with very small pearls,
rice pearls, etc.). Even with small pearls I will knot at intervals
of, say, 2 to 4, depending. Not only do the pearls drape better, but
the knots provide an important cushion against abrasion. Imo,
generally (and there are always exceptions to rules) the absence of
knotting cheapens the look and performance of strung beads. In the
case of a strand of classic, cultured pearls ( I assume they're
round?) I would expect them to be knotted.
I wonder if this may be a situation where the pearls were imported
exactly as you describe. Sometimes I see what is essentially raw
material (i.e. beads) intended for restringing being sold with a
clasp attached. Some years ago when that first began, I was told by
an importer that it had to do with a change in import duty charges
with regard to "finished" jewelry vs. "unfinished" bead strands.
Throwing a clasp on the strands, even stuff strung on the usual fish
line, made the strands "finished", therefore, cheaper to import - so
I was told. Plenty of material still came (comes) into the country in
the usual, unfinished manner. I don't know if that still applies...or
applies to this case.