25 CFR § 304.4 - Standards and additional requirements.
No piece of silver, though made in compliance with the standards set forth by the Indian Arts and Crafts Board, shall bear the Government mark unless:
(a) Its weight is substantially in accord with Indian usage and custom.
(b) Its design elements are substantially in accord with Indian usage and tradition.
(c) Its workmanship is substantially that expected in good hand craftsmanship.