The use of baby teeth (or "milk teeth") in jewelry has nothing to do with mourning. Quite the opposite - during the 19th century it was well worth celebrating if your child survived long enough to lose their first teeth. Thus, the Victorians (a sentimental and not-too-squeamish bunch) commissioned jewelry made from these tiny treasures. This lovely version of the style, pictured at the very bottom of this stack, features a crossover design with two milk teeth and a 4mm ruby. 14k gold. Size 6.5.
Milk Teeth & Ruby Crossover Ring