I’ve had this problem with rubies. Often you will find that not all
the holes are the same size. I usually begin buy setting out lengths
of wire, looped on one end, in 24, 26, and 28 gauge, then trying
the wire (thickest first) on each bead, until I find a size that it
fits on (if they don’t fit on 28, I put them aside for a wire
crochet project I keep hoping to get around to). When I find the
size that fits, I slip the bead down on the wire and go on to the
next bead-- tedious process, but at the end, all the beads are
sorted by hole size.
I haven’t used Softflex in a while (I much prefer it to Beadalon)
but, if I remember correctly, they make a beading wire fine enough to
string the “26 gauge beads.” If I want to use the 28 gauge beads, I
use wire wrapped links–a somewhat fussy process at that size and
gauge, and I’ve only used it for earrings.