Dear Finfan,
The earliest molded Bohemian beads were produced using a tong mold with a fixed perforator. The perforator was conical because of it's fixed position (this shape allowing it to withdraw in an arc and not disturb the shape of the resulting bead). It was not unusual for two unwanted things to happen: 1) if the pressure were not great enough, sometimes the perforator did not make an effective exit, resulting in an aperture that was really small; and 2) it was pretty common for the small aperture to break-away, leaving a slightly conical crater.
These features inspired Lester Ross to propose a manufacturing sequence that involved unnecessary steps—resulting in what he has called a "mandrel-pressed" bead. I disagree with his expression of this method. These are just tong-molded beads. The most famous of these beads are those made from Vaseline glass—a glass colored with uranium, that gives it a greenish-yellow color that is fluorescent (and minorly radioactive).
However, like many molded beads, they come out of the mold with "flash"—excess glass that was squeezed out of the mold at the seams/joins and hangs on at the equator or seam-line. Once the bead had cooled and hardened, the flash was broken off, and usually some touch-up work was pursued. Some beads would be tumbled in abrasives to smooth-down the mold seam. But because these particular tong-molded beads are faceted, they were usually touched up to enhance the faceting. This is why the beads have some individuality in their shapes.
A later improvement of the process was the tong mold with a spring-released perforator. This device forces a perforation into the bead and then withdraws in one operation, and because of the action, it can be a simple cylinder. So later molded beads didn't have to have obviously conical perforations.
I hope this is helpful. A lot of the above was worked-out by Elizabeth Harris, but I was also involved in these issues of the day, some years ago. Unfortunately, many early tong-molded bead are called "Vaseline" beads even when made from a different glass, because the name is used to indicate the typical conformations (including the conical hole). There is no such thing as a "teal Vaseline glass bead," or a "red Vaseline glass bead"—but because the name "early fixed-perforator tong-molded bead" is not sexy, people will grasp at having a name.
Jamey
If I can lay my hands on them, I'll post an image.
Mine have a sort of iridescence to them, too. They are some of the first vintage/antique beads I found when I started buying beads. A lot of people don't care for them--one customer reneged on purchasing a special-order bracelet because I used one in the design. (She said it was too "gaudy".) But I like 'em!