What metals, materials, etc. would you use for golarion cultivation tiers?

So I'm running Season of Ghosts, and I thought it'd be fun to give a bit of flavour to the players' tian xia adventure.

Honestly with how the levels and spell levels are laid out, I feel like there's already the perfect structure just waiting for names.

If you had to pick a metal or material (or something else) as a name for each "cultivation tier" to fit golarion, what would you pick?

For example, I feel there's more that can be done past "copper bronze iron steel silver gold mithril adamantine etc" with so many interesting materials.

I was looking at materials on AoN last night and already saw so many options. I'd love to hear from anyone more versed than me in golarion lore and what not with how some of these could co-incide!

If I can have it feel more special and unique, that'd be super awesome!