Perhaps the disagreement hinges on which definition is being cited.
FTC regs require that items labeled silver, sterling silver or 925
be at least 92.5% silver. The FTC does not state that the balance
must be copper and nothing else. Follow the links for the verbatim-
http://www.silversmithing.com/1stamp.htm##23.6
http://www.ftc.gov/bcp/conline/pubs/products/indianart.pdf This is of
course a legal definition, and one specific to the US.
Lee Einer
Dos Manos Jewelry
http://www.dosmanosjewelry.com