The difference between trademark infringement and copyright infringement is that trademark law protects the mark itself, not necessarily the object to which it is applied, whereas copyright protects the object/image itself regardless of any manufacturers mark.
If I create an entirely new board game and print on it Hasbro's trademark, Hasbro can sue me for trademark infringement, as I am attempting to pass off the new product as one of theirs, attempting to rely upon their good name to sell my game. But the product itself, being a new creation, is not considered to be a Hasbro product simply for being marked with a false maker's mark.
If I publish an exact copy of the game Monopoly and leave off any of the owner's trademarks, replacing them with invented marks, I will be infringing on the owner's copyright, even though there are none of its protected marks present on the pirated object.
Trademarks must be registered to be protected. Copyright inheres upon first publication even without registration, though registration makes suing for infringement easier as it establishes when the piece was created.
Also, a closer reading of the government's guide for jewelers, which I ought to have done before my last post (mea culpa), shows that there is a formula for marking unusual alloys of platinum in which the alloying metals are not elements in the platinum group. It's based on x parts per 1000, and can be used where platinum is at least 50% of the alloy.
For instance, let's say you make an alloy that is 75% platinum and 25% sterling. Since sterling is 92.5% silver and 7.5% copper that would make this alloy 231 parts silver and 19 parts copper (rounding to the nearest whole number). The quality mark for this would be:
750Pt 231Ag 19Cu.
The germane section is paragraph c subparagarph 5: