What is the practical difference to you for stacking up on 1 oz .9999 silver rounds vs. the same ASW coin but lower fineness (e.g. 1980 Mexico Onza: 0.925 fineness with 33.625 grams total weight = 0.9999 silver)? Assuming that they're the same cost, the weight differences are negligible, the balance metal's value is ignored, etc., do commercial precious metals refineries (I like to call them "melt-ups" lol) pay less for the same ASW with less fineness due to more refining that's involved? From how I understand it, they pay by ASW, and no premium is given for higher fineness. And, I'm a collector so I don't go the melt-up route. So, what is the practical difference for the governments and Mints to make 1 oz silver rounds in .999+ fineness? Is it simply the image / perception that you have 1 oz of pure silver on hand, which helps the Mints the world over to generate more sales relative to the same ASW but less fineness counterparts? To put it another way, why doesn't the US Mint produce sterling silver 1 oz ASW bullion coins instead? It's not like pure silver rounds are more robust in any sense - it's worse in almost every physical characteristic besides being a lower overall weight (e.g. more susceptible to tarnishing, softer, etc.).
It's cheaper to get 999 planchets; that's why the USMint is switching over to those rather than the 90%ers.
But couldn't they simply charge a small or even large premium for a visibly bigger round? I'd prefer a 1 oz ASW of silver in, say, Argentium 960 silver - it'd be a little bigger but will be a more robust sterling silver round, which is especially beneficial if collectors are looking to pass on their collection to the next generation. Probably less susceptible to milk spots, too, and definitely more resistant to tarnishing with an ultra mirror shine.
They pay higher rates the more pure it is. So .999 will garner the best rate as they won't have to separate any base metals from the silver. However you can pretty much always find people paying better than a refiner unless the coin is nearly unrecognizable. (so to me its pretty much irrelevant what refiners pay)
From a collector's standpoint, would the same design, same ASW, and mintage coin, but larger coin be more valuable? My hunch is that, all else constant, they'll all remain equally as valuable in terms of their numismatic value. However, perhaps the .999 silver rounds may be worth more in higher grades because fewer and fewer will survive in high grades when left raw. Not sure that there's sufficient numbers of losing high grades on moderns, as so many of them are sent to get graded and never leave their slabs.
lol I go off on a tangent a lot. Anyway, I was wondering if .999 silver rounds were simply demanded more by collectors, which may be influencing the Mints' decisions, perhaps more so than cost reasons as Mints can sell lower fineness but same ASW at a premium for what would be larger rounds.
Yes I believe .999 coins are considered more desirable by the collecting community. (well at least the more bullion oriented collecting community) All the new government bullion, eagle, maple leaf, panda, philharmonic, brittania are .999
The use of 90% or sterling in modern coins is more of a nostalgic thing. There is no practical reason for making modern silver coins with anything other than .999 silver. Even .9999 is more of a marketing thing. Who is really going to care about measuring down to the 1/10,000 of a percent? Using .999 silver is actually easier for coinage and results in more consistent quality. The 90% or sterling alloys are harder to work with and have a higher reject rate. ...or so the Mint says...