Such portraits appeared between the 1790s and 1820s in the courts and affluent households of England, Russia, France and even, quite rarely, America. In all, Weber estimates that fewer than a thousand were produced. Eventually, not just lovers but beloved family members were portrayed. One bracelet, for instance, is composed of four eyes, each belonging to a member of one family and bearing the initials of each individual. Mourning pieces contained the eye of a departed loved one, sometimes set in a frame of pearls which symbolized tears.
Larger pieces can be expensive.
In the 18th century, if you couldn't afford ivory, you could commission less expensive paintings on vellum, a paper thicker than parchment. Today, however, paper miniatures are no less valuable than their ivory counterparts. Rings are often worth more than broaches because they are rarer. Larger pieces can be extraordinarily costly. Fine detail in the eye also increases value.