@juanelric
"sexless" is not "genderless".
SU gems are sexless, but feminine in gender.
The gems in Houseki no Kuni are both sexless and non-gendered/agender/non-binary, and this has been confirmed to the official English translators by the author; specifying that 'they/them' is the appropriate term to use in English.
Also, worth mentioning that gender is not "psychological", it's neurological (being an emergent property of the brain's structure, which is biological).
You're either referring to sex, or referring to gender; referring to the former with a term like "biological gender" is silly.