A Question for the Ages

Why are both Ps in sapphire silent?

I can understand the second, which is followed by an H, but the first one is not.

So as far as I’m concerned, I’m going to pronounce it sapfire from now on.

Fortunately, I don’t deal in gemstones or gin much, so I won’t actually have to do this and make people think I’m ignorant instead of taking a principled stand for a more obvious pronunciation.