Titanium. Forged carbon. Carbon fiber. Bronze. And now sapphire:

(Image credit: K&H)
All the materials on that list have followed a common pattern:
- High-end watchmaker spends R&D funds to learn how to make watch cases out of it
- Other watchmakers learn, adopt/copy
- Prices drop precipitously.
Sapphire, I think first used in a six-figure Richard Mille, is now heading towards affordable, and though I’ve not checked prices I hope to see one in person soon. I as part of my RSS habit, I follow the Korpela and Hofs blog and they just shared the above image – a sapphire case from Hong Kong-based Bright Sapphire. Here’s another image from Bright:

Anyway, cool, should make for some fun watches when it gets down to sub-thousand-dollar pricing.
A bit of background: Titanium was kind of an IWC thing, Panerai did bronze, Audemars Piguet carbon fiber. Read more about sapphire cases here, here and here.