I believe that's the one in the National Museum Wales, looks like the same set we saw a few years ago. The spiral bead can be horned or more flattened as the one in the photo too. The technique to produce that particular style is much-debated and as yet no one has been able to reproduce the style. We think it's a blend of furnace-work to produce the spiral cane, along with beadmaking techniques.
There are also a lot of variations on a theme of spirals, but the beadmaker has a lot of input into the final appearance as the one from the field find is much more of a flush appearance as opposed to the Welsh bead. There are similar beads from Scotland, too.
Unfortunately, the most recent (and only) publication on beads in general from the IA and Romano-British periods is the Guido book, which is a bit out of date as so many beads have been found since then but it's still a great starting place for classifying bead finds.
There are also a lot of variations on a theme of spirals, but the beadmaker has a lot of input into the final appearance as the one from the field find is much more of a flush appearance as opposed to the Welsh bead. There are similar beads from Scotland, too.
Unfortunately, the most recent (and only) publication on beads in general from the IA and Romano-British periods is the Guido book, which is a bit out of date as so many beads have been found since then but it's still a great starting place for classifying bead finds.
Prime practitioner of headology, with a side order of melting glass with a stern glare.