My girlfriend and I made pendants with eachothers blood which we wear pretty much all the time. You can easily find 'test tube' or 'vial' pendants on amazon and etsy, usually marketed for keeping ashes. Make sure you are familiar with anticoagulant.
My blood is in the one on the left and my girlfriends is in the right. This picture was taken when the blood was still fresh, which is why the one on the right is so bright. My blood naturally starts much darker. You will also notice mine has a small gradient near the top. We have decided that this was probably caused by hemolysis, since my blood was treated very roughly when being transferred to a vacutainer. My girlfriends appears much lighter than it ordinarily would since it greater than double the amount of sodium citrate than would ordinarily be used.
They will get crusty with time, but if you didn't contaminate them with any sort of bacteria when making them they will not really get gross. It's important to remember that like anything you use blood for, it will very quickly lose its vibrance. You will also probably have to invert them a couple times every morning to mix the plasma back in.