Smokey Banded Agate pendant, the gemstone of Afghanistan origin, the cut by hand in Kabul Afghanistan, based on an ancient Bactrian bead/pendant form, with a slight twist, for mostly this type of bead, when excavated in the north of the country, is triangular in form.
When put up against the light the striations and muted colours in this gemstone are quite lovely.
The images in the above gallery for this Smokey Banded Agate show both sides of the piece.

The 45cms box-link Silver chain would add $35 to the price.