"We're getting old," he said. "No," said Paula Zarte. "You are. I'm just not as young as I was." - Jon Courtenay Grimwood

Immortality had been perfected, at least in its non-biological forms, but insufficient attention had been paid to the boredom of eternity and the corrosive nature of the ratchet effect which demanded ever sharper, stronger and more intense sensations to maintain something like the same level of satisfaction.
Living forever turned out to be much like long-term sex, psychologically tricky; which was why what killed the original colonists was not hardship but boredom.

Why would we do this? she asked, watching smoke trickle towards the ceiling. A whole world of rigid rules covering temperature, convection and Brownian motion all busily pretending to be truly chaotic.

The fifty-third Chuang Tzu wore the very first on his cloak as a diamond buckle. Every emperor became a diamond eventually. It was one of the few advantages of living as a carbon-based life form.