'Rare' in the Bible

There is gold and abundance of rubies; but the lips of knowledge are a rare jewel.

by knowledge the rooms are filled with all rare and beautiful treasure.

I will make people more rare than fine gold, even a person than the pure gold of Ophir.

It is a rare thing that the king requires, and there is no other who can show it before the king, except the gods, whose dwelling is not with flesh.