Shears can really achieve prefixes but players are not allowed to inbay gems on them. However, they are a special kind of digging tools so should fit gems that provide effects for digging tools.

I tested 33 out of 35 distinct perfect gems on shears in Craftoria 1.23.0, which includes Apotheosis 8.3.6 on Minecraft 1.21.1. The modpack includes a mod providing gems with bonuses to Iron's Spells n' Spellbooks; these gems were also tested.
The two gems I did not test are from Apotheosis' native Twilight Forest integration. After code inspection, they don't list shears as a valid target.
Of the 33 gems I tested, only the Endersurge Gem will fit on shears; all other gems won't fit. This is because no other gem lists shears as a valid target.