[totallyabstract]

Presumably two different instances of this clock would have different tick rates due to the specific crystal used and it's very difficult to produce two identical crystals.

An atomic clock is very consistent across devices as it exploits the properties of an element which is much more repeatable (just have to have a quantity of the element).

[dwd]

Reminds of the Anne McCaffrey Crystal Singer series where crystals were mined for use in their space-faring technology. Each crystal was unique and would be tuned to a particular use.

https://en.wikipedia.org/wiki/Crystal_Singer