I wasn't finding just the right bead in my stash the other day for an upcoming project. Then it dawned on me....crackled glass marbles! That's what I needed! This technique has been around for a long time and it is sometimes called fried glass marbles.
In the past I've bought crackled beads.....But it's so easy to do.
I put some glass marbles in an aluminum tray and got my little toaster oven out, the one that I use just for crafting, and set the temperature for 350F. Once the oven hit 350F I put the marbles in the oven for 20 minutes. When the 20 minutes was up I removed the tray with oven mitts on and I dumped the marbles in a plastic bowl of cold ice water and within minutes I had some really cool looking patterns in the glass. I didn't have safety goggles on so I made sure that I wasn't directly over the water bowl just in case some glass broke. None did, but you do hear hissing and crackling.
I baked some small round ones and some flat back ones. The process is known as thermal shock - the glass is heated and expands unevenly and when you dump them in the ice water it is forced to cool unevenly. It crackles on the inside only. And, this is something that you cannot do with all glass.
I think that they look nice and sparkly.