Happy Hump Day everyone 🙂 Time for another riddle to work your brain!

More precious than rubies
And redder than wine.
Everyone needs me,
All of the time.
But when one is murdered,
And lying there slain,
Then you can find me,
Without searching in vein.

If you think you know the correct answer please post it in the comment section below. Once the correct answer is posted I will confirm 😉

Good luck!