How do you say crystal in elf?

There is no single, universal language for elves in fantasy literature. Each author creates their own languages, often drawing inspiration from real-world languages or creating entirely new ones.

To find out how "crystal" is said in a specific elf language, you'd need to consult the source material. For example:

* J.R.R. Tolkien's Elvish languages: You might find the word in Tolkien's works, perhaps in "The Silmarillion" or "The Lord of the Rings."

* Other fantasy novels: If you're interested in a specific fantasy series, check the author's website or fan communities for information on their invented languages.

Without knowing which fictional world or author you're interested in, it's impossible to give you a definitive answer.