Just looking at the picture one would tend to believe that the bead is likely a Pyu-Tircul early etched bead.

It is very similar to some that I have, one with the stripes on the end and one without. The etching looks very good to me, I would say it is ancient at first glance.

What concerns me though is the large size. The only similar Pyu-Tircul beads I have seen are about half that size. The ones in my pictures below are about 6 x 16 mm in size.

Beautiful bead though. I would say that you must be certain of trust in your seller and consider the price.

Happy collecting,

Jan Skipper, Mosquitobay