The lack of a grading system for the popular stone has prompted a father-son team to spend the last five years working on one.

Collectors say that relicarios, made from whatever the artisan had at hand, are often overlooked in the study of colonial-era art.

Native American artisans create molds from cuttlebone and tufa stone to cast metal jewelry.

While the jewelry fad has waned, artisans continue to make designs in silver and turquoise.