The semiconductor industry calls the cuts of a crystal die or dice. Is this term outside of semiconducting industries correct too?
For example, a crystal has been cut into small plates. What are the plates called then?
In this context, the term "die" really only applies to the semiconductor industry. Depending on the industry, the terms "slice" or "sheet" might be better suited.
In your example of crystals, if you are specifically referring to piezoelectric crystals of the variety used in the semiconductor industry, the process involves dicing quartz plates in to what are known as "blanks", the blanks are then lapped and further processed before grading and finishing up as what's called a "quartz oscillator-plate" or "piezoid".
Back 1972-1974 I worked in the RCA CMOS LSI design shop in Camden NJ. The slices of semiconductor we used (but never actually touched) were referred to as wafers. I don't recall ever hearing another term used. We worked with both silicon and sapphire wafers. (Our shop never worked with germanium, that I know of.)
(Of course, this term applies to a thin, flat, uniform slice, used for integrated circuits and solar cells, not random bits chopped off while forming, say, a ruby into a multi-faceted gemstone.)
A piece of a wafer is called a "die" (and is produced by "dicing" the wafer, after the desired circuitry is first printed/baked onto the semiconductor surface.) My understanding is that that term comes originally from the cook's action of dicing vegetables, not the cubic piece used in gambling.