SEARCH for the treasure...
I don't see how lower thermal conductivity could be "dangerous". It just wouldn't cool as well as other options.
I tried my stainless steel balls last night. Really impressive cooling! Much better than quartz. They are heavier though. And damn, the lower part of my stem has never been hotter immediately post-hit. So they grab a lot of heat.
I still think sapphire is technically the best option for cooling beads. They seem to grab more heat, but without getting as hot to the touch. And they're much lighter. However, sapphire costs like 10 times more than stainless steel.
I'll put it this way. My short stem with 4mm SS balls cools better than my long stems full of quartz.
So far my ball ranking is:
2.) Stainless Steel
I use 3mm SS316L balls in the CU mod, working great. For my small Herbolizer globe I use 6mm Quartz balls, while sapphire balls are potentially better, 450 balls would be even more expensive then my quartz balls, and I’m sure I would not know the difference.