Leni...
On the other post it would be off topic if I respond to it. So... I'll share with you why I know that is a 19th century chevron bead. Chevrons were popular since the fifteenth century or so but older ones like that usually have at least seven layers. Later during the 19th century African trade the beads were reduced to six layers and there were tons and tons of them still existing in Africa up to and during the twentieth century. In fact they are still being sold at antique shows and flea markets throughout the US... Ironic... heh...
The value depends on the size. Big ones sell for hundreds.
Chevrons were also traded in the US but are rare and mostly 18th century seven layer beads, Louis and Clark's route I think is where they are most commonly found.
The bead you have is a nearly perfect specimen.