Gold and silver are qualitatively different and that's that. They require different amounts of labor to produce (and perhaps method, idk) and they have different uses. For example, the James Webb space telescope has gold-plated mirrors — silver has different chemical properties and would not satisfy the same function.

Whether something is a use value, or is not, is determined by whether it is consumed and therefore reproduced with regularity by an established industry.

The way I understand the way Marx is using "qualitatively different" is both in its obvious form, gold and silver (as simple commodities) are different from one another, but importantly that it is about qualitatively different forms of private labor confronting each other in exchange. If I am spinning, weaving and tailoring my own coat, neither the wool, thread, linen, or coat confront each other as commodities in exchange even if they each have a use-value, but once you have a division of labour, those use-values can confront each other as commodities in exchange.

(I'm struggling to word a more specific example when considering gold and silver as commodity-money, so may be someone can jump in with that.)

The rest of the quote you posted seems to get into this.

In a society whose products generally assume the form of commodities, i.e. in a society of commodity producers, this qualitative difference between the useful forms of labour which are carried on independently and privately by individual producers develops into a complex system, a social division of labour.

and another in the paragraph before:

“The totality of heterogeneous use-values or physical commodities reflects a totality of similarly heterogeneous forms of useful labour, which differ in order, genus, species and variety: in short, a social division of labour. This division of labour is a necessary condition for commodity production, although the converse does not hold; commodity production is not a necessary condition for the social division of labour. [...] to take an example nearer home, labour is systematically divided in every factory, but the workers do not bring about this division by exchanging their individual products. Only the products of mutually independent acts of labour, performed in isolation, can confront each other as commodities.” p 132 (Fowkes)

This last part is interesting to me when you think about how large firms operate even today. If a single firm produces multiple of its own inputs and outputs, they do not actually confront eachother as commodities (in a market). As an aside, one of the more compelling arguments against the ECP has been its own critics inability to determine exactly where it becomes impossible to calculate production as one firm gobbles up another firm which produces its own input.

I recommend either reading Marx directly or reading a more modern summaries like those from Heinrich or Michael Roberts.

Now is a really good time to read Marx directly because you can discuss it with other hexbears in the same situation!

Why not just read that yourself? Or set up another thread.

Marx highlights this as "absurd" in order to acknowledge that the reader might think Marx has lost his mind when he claims that society does all these crazy mental gymnastics in order to produce. He's saying, "Yes, it is crazy, but it actually works this way."

it's "absurd" because we go through this ridiculous Rube Goldberg of an economic system just to "intelligently" distribute the total social labor. And to be seen, in order for some people to live off of the work of others.

I may not fully understand your question so apologies if I am speaking in a different direction.

In this case, Marx understands value as having a form primarily in exchange and in anticipation of exchange, the idea being to increase total capital through production and sale. Capital becomes represented by the money form so that exchange need not be directly understood as linen yards to coats to hammers, but we also know that money itself, exchange, is representing exactly that. A coat is $50, a yard of linen is $15, a hammer is $20, so they all implicitly relate to one another, at a moment in time, via the act of exchange and via the potential to be exchanged.

Producers, if you mean the bourgeois, are doing this because they want to increase their profits and they (attempt to) understand their costs vs. intended sale values so that they accumulate a larger volume of capital tgaty they will use to "outcompete" their rivals by repeating this process better than them. But we are all subject to this idea of value, as we buy the coat and the hammer (and maybe sometimes the linen), by definition for its perceived use value (Marx didn't try to distinguish an idea of valid or necessary use value from the rest, which was a good call).

Done