What evolves with a moon stone in sapphire?

You're likely thinking of Nidoran♀, the female Pokémon that evolves into Nidorina with a Moon Stone. Nidorina then evolves into Nidoqueen with a Moon Stone.

However, there is no Pokémon that evolves into Sapphire with a Moon Stone.

Sapphire is a gemstone, not a Pokémon. Perhaps you're thinking of a different Pokémon or a different evolution method.