Travis, I looked at Stuart's web site and the third and fourth sheaths are both arrowhead basket weave and I didn't see any grain type stamping on either of them. I went into great detail explaining the arrowhead and then realized that wasn't what you were asking so I deleted it as wrong information.
My pebble grain stamps are Bob Beard's Pro Series and are really kind of expensive, and generally have to be special ordered so there is quite a wait period. Tandy/Leather factory has similar stamps in the E294 series in four different sizes and shapes. (E294-00, E294-01, E294-03, and E294-04). These are also MUCH less expensive. Check the Tandy/LF web site and other leather craft vendors as well.
Paul