Please don't take this suggestion literally. I'm totally talking fake here. Some boiled down strawberry Ribena or watered down red jam should do the trick. It's just a sweet romantic gesture; just for the sentiment.
Buy a nice silver chain and a small see-through vial/glass bottle to pour the 'blood' in.
Valentine's Idea no. 34: Do an Angelina Jolie - Give Your Lover a Vial of Your Blood...
Labels: valentine's day, valentine's day idea, vial of blood