Crackle beads have a pretty neat look. Basically, the crackle look is created when the bead is dropped into cold water while they are still hot; this process causes cracks in the glass.
There are some crackle beads that are painted with a crackle look, but are not true crackle beads.
Some find crackle beads weak, as they are literally cracked. I have never had any more problems with glass crackle beads than I have had with any other glass beads.
Although I’ve only featured round beads, you can find crackle beads in any shapes and sizes.