Glass: Hanging Systems
Besides the standard metal cap with hook other hanging methods have been used. Here are some of the various hanging systems.
Early hanging system being a cork, with an inserted metal hook, firmly set in the pike.

Ornament diam 5cm

Ornament diam 5,5cm
Kugel caps, cap 3 is only one variation in design of others, many shown in the book Christmas Rarities by J.Lightner

Silver kugel, small, diam 4,5cm, cap 3

Light green kugel, diam 10cm, cap 4

Cap 6, top and side view; silver kugel, large, diam

Cap 5, top and side view; red kugel, large, diam 24cm

Silver, 10cm high, cap 7, New?

Metal hook inserted directly in the pike

The pike is fully open with rounded edge and the hook fits loosely

The pike tapers to the top and the hook is fixed firmly
Early metal caps, glued in the pike

Metal wire wrapped with fabric and fixed (glued?) into the pike

These are the US WW2 war time caps which were paper, and paper and string.
Information thanks to and pictures property of Jeffrey Magadanz.
Glass hooks

Ajeko, annealed hook

Art glass, annealed hook color sometimes matching some part of the ornament

Art glass, annealed hook of milkglass deer, and red hook from pelikan with red paws

Glass hook part of ornament, not annealed
Standard ornaments with glass hook
At one time they were classified as Ajeko, but clearly they were not