I always find eyes intriguing, I guess that's why they say eyes are called windows to the soul. Eyes can be very creepy at the same time because they indicate something is alive and it is aware of your presence. The blinking eye in the opening sequence of The Twilight Zone used to give me goosebumps even when the opening tone (opening music?) didn't.
I found the photo of this necklace made from old glass prosthetic eyes. With a little digging I found that most vintage glass eyes were made in Germany, and those eyes are often very well-made enough to be almost indistinguishable from real eyes.
To make your own version, you can get these plastic doll eyes from eBay, they are much cheaper than real vintage glass eyes (This is not my hand). First gather some red fibers from something like a red sweater. I use a bottle of slightly old (therefore slightly yellow) clear nail polish and brush a thick layer on to the eyeballs. Right after the nail polish become tacky but before it dries completely, stick the red fibers onto the eyeball. Apply a few at first and find an image of a real eyeball as a reference. Notice there are usually more blood vessels near the edge of the eyeball and around the iris, and make sure they are generally in a radio pattern. After the nail polish dries, apply a few more layer.
This is what it looks like after the final layer of nail polish dried. I wish the iris could look more realistic, but I haven't found a good way to fix that yet.