I use Coors ceramic mortar and pestles. I bought my last one on the mid 1980's. It's never given me any trouble. The company got renamed at some point. It's now CoorsTek out of Golden Colorado, USA. Easy to find online.
They have a sturdy, tough construction, and are used in laboratories worldwide.
The key feature I like about these sets is that the pestle curve matches the mortar curve through a wide range of angles. That increases the efficiency of grinding. I've looked at Marble, granite and lava units over the years, and have seldom come across a pestle that's a decent fit for the mortar. That flaw causes frustration and an irregular grind.
Maybe some day I'll find a better pair, but it's been over 30 years now.