Typically, when these sorts of beads were made (at a "lamp"—the device invented at Venice, and used by Europeans, and those who learned from them), the essentIal process was this:

The beadmaker would take two preformed canes, and hold them parallel. (OR, it could be that two prepared canes were previously conjoined. It does not matter which.) These canes were nearly always a white cane and a colored cane. The colors that have been seen are brown (the most-common color), green, blue, yellow, and red—all of these being translucent. The canes were heated to plasticity, and applied to a mandrel to make an oblate wound bead. (Much less often, cylinders and fusiform shapes.). The first winding onto the mandrel created the base. In viewing these beads, most often, the beads will be seen to be white at one aperture, and colored at the opposite aperture. (This is how we know two canes were used simultaneously.)

Once the base had been created, the beadmaker pulled-back to attenuate the two-colored canes into a trail. And he/she continued to wind the glass onto the base, building up its shape. These windings can be fairly uniform or consistent (like neatly adding thread onto a spool)—resulting in a bead that has parallel, but random-looking horizontal stripes, parallel to the equator of the bead. This provides a visual effect that is "agate-like." Thus, my name for this class of beads—"agate-glass."

Nevertheless, with many such beads, the beadmaker occasionally allows the trail to cross previous winds, and/or to form waves and loops. And this was probably done to give the beads a more "naturalistic" appearance, and therefore seem as though they have random banding—as would be the appearance of actual banded agates.

And, in a few instances, the outside windings can be placed OVER the ends of the beads—which covers the white or brown ends, making them become hidden. But, I am reasonably confident that a broken bead would reveal the structure I have described.

If the inside is not "brown (or color of choice) on one end, and white on the other," then it is possible that a DIFFERENT agate-glass bead was made—and this is certainly possible.

One of the reasons these beads remain a mystery is because they do not routinely appear on sample cards. One could postulate that either the beads were manufactured before samples cards became common (after ca. 1825); or that the companies that made these beads did not exploit sample cards over the times of manufacture (whenever that may have been, before or after ca. 1825).

The glasses that were exploited are visually-similar to glasses we know were used by Venetians, and possibly/probably Bohemians. I suppose only a chemical analysis would confirm or cancel ideas of visual similarity that seem to point to manufacturing origins, and possible times. But, I remain confident that these beads are "trade beads," and that they derive from much more recently than "2,500 years ago," nor from any of the other proposed "ancient sources" that made beads prior to the exploitation of lampworking.

JDA.