Blood Amulets require: Magical amulet + Amn Rune + 1 Perfect Ruby + 1 magical Jewel. Preset mods are 1-4% life leech, +10-20 life, 5-10% Faster Run.
Nice random stats on the left one, but it's too bad no one plays Elemental Druids. The one on the right is about as good a dual leech as you can get for the Clvl. It would be a godly amulet if there were a good +1 or +2 skill bonus to a melee character, but you can't have everything.
The Necro amulet on the left is interesting and shows how useful rolling a new amulet can be. The main bonus you usually think of on a blood amulet is life leech, which is useless to most Necromancers. However the +hps and faster run are useful to anyone, and this one rolled more life, +1 necromancer, and big resistance, making it an excellent necromancer amulet. The amulet on the right shows the big Clvl req problem you often get while crafting, but the random mods are excellent.