From Diablo Wiki
Sapphire gems are no longer in the game
Sapphires are one of the six types of gems found in Diablo III.
The full stats for Sapphires are not yet known. The only information we have about their bonuses came from players observing the stats on sapphires found in the Blizzcon 2010 demo. These bonuses and values may change in the final game.
- Weapon: +3% Life Stolen per Hit
- Helm: 3% Better Chance of Finding Magical Items
- Other: +4 Willpower
It's not yet known how much these values will scale up with higher level gems.