For completeness’ sake, here is a link to a somewhat disturbing, although scientifically interesting jewelry company.

Basically these guys take bone samples from a couple and will bioengineer rings made of each other’s bone tissue.

Awww, that’s sweet, isn’t it? It’s specifically made for couples who are so close that they absolutely must be able to literally feel the other person at all times. It’s not a good idea to lose one of these things down the drain, since it’s likely to be quite hard to get another one made. Er, painful that is.