With reference to the points made by Alejandro, Hans, and Makoto.
My view on this, rather bizarre, aside in ch 1 vol 1 is similar,
more or less, to Makoto's point 3, ie that the labour that has gone
into the discovery of diamonds for 'eighty years ending in 1823' has
not been accounted for as a reproduction cost. The quote is in the
context of the argument that increases in the productivity of
labour reduce value per unit. Perhaps for extremely infertile mines
Marx thought that the social mechanism which accounted for the
labour that had gone into a tiny volume of the commodity, particularly
over a very long period of time, was necessarily deficient.
Costas