@Oiseaux it's a little hard to see and its only visible in one of the pictures of the necklaces. I zoomed in the image and wrote out what I think I see on the bead. I think it could also read 4,5. Very difficult to see what the first number/letter is.
Hmm, I see what you mean. It does look like there's something written on there - maybe the logo or initials of a brand or jewelry maker? I'll poke around and see if there's anything that looks like that. Looking at the one that is mostly blue, the first character almost looks like a turtle shape (which, in a surfer-style necklace like this, wouldn't be too weird).
I like to make jewelry as a hobby, and I'm trying to figure these necklaces out. These are what are often called "seed beads," made of glass or ceramic, and very common and inexpensive. Stylistically they could be associated with southwestern/Indigenous American or "southern California surfer" styles, among others. I can't tell offhand how long the necklaces are (although with the measurement sample, it's probably possible), but these look just barely long enough to pull over one's head. A store purchased necklace often has a clasp if it isn't super long (like 30") so it's easier to put over your head. These don't, unless the little thing we're looking at is a magnetic or other non-traditional type of clasp. I don't think that's likely, though, since that type of clasp is expensive and usually used with higher-end beads, like gemstones; the materials in these necklaces are pretty inexpensive and casual.
The mystery bead could also be a focal bead (like a pendant in the middle of the front of a necklace); focal beads add cost, too, though, so I'm not sure why it would have one but not the other. Some brands also add on a little logo bead or tag on their jewelry (Pura Vida is an example I'm thinking of, with little stamped metal tags on their bracelets).
So if I had to guess, these are either:
-homemade necklaces, and the mystery bead is a decorative focal bead and the motif on it is a design;
-or made by a business that is keeping costs low, and the bead has their logo on it;
-or possibly made by a small artisan who has added a bead with their logo.
I'm not even sure if figuring out the provenance of the necklaces would help with gathering info on this person, but hopefully that helps a little!