I would be happy to check one for you if you want to send one. If you don't want to break the strand, and are willing to do this - the hot needle test is very informative. If there is enough slack you can touch a hot needle point just inside the hole on one. If it sinks in readily and you get a burning plastic smell then you probably have polystyrene beads. Acrylic (Lucite) is another possibility but Lucite beads normally look glossier and they will "feel heavier" than polystyrene, which is about the density of natural amber. Polyester beads are even denser than Lucite but generally have a soft matte finish. Without samples of these three plastics you probably won't be able to tell the odor of one plastic from another.

If the needle will not sink in at all then you could have a thermoset plastic like Bakelite but Bakelite is one of the densest plastic and "feels heavy". And your strand does not look like old Bakelite (also known as phenolic resin).