Bombay Jewellers Ltd. v. The Queen,  GSTC 94 (TCC)
The registrant, a jeweller, purchased gold bars with 99% purity on an exempt basis, and then cut the bars (sometimes with further modeling or rolling) into smaller rectilinear pieces, which it then sold to customers without charging GST. After noting the reliance by the registrant on the ordinary dictionary meanings of "bar," "ingot" and "wafer," Margenson J found that these terms should be given their technical rather than ordinary meaning. Accordingly, the pieces were required to have a readily ascertainable value, in order that they generally were readily transferable. Because the pieces instead had been tranformed out of standard deliverable form, this requirement was not satisfied as it was obvious that no bank or gold dealer would accept them for delivery without first having them assayed and weighed. Accordingly, the pieces did not qualify as "precious metals" as defined, and their sale was taxable.
GST Memorandum (New Series), 17.1
a precious metal bar, ingot or wafer must generally be recognized and accepted for trading on Canadian financial markets, so that ordinarily they will bear markings indicating their purity level and the issuing refinery or institution (para. 28).
Policy Statement , P-192 "Supplies of Precious Metals", 11 November 1995 (obsolete)
a Government of Canada silver maple lead coin bearing markings that indicate that it has a purity of 99.99% and that it may be used as currency (but with no stamp of a refiner or any serial number) would qualify.