This is interesting if you include jewelry and similar, buying or selling. https://mjsa.org/publicationsmedia/mjsa_journal/karat_concerns/
I'm concerned about this because of how it could change the general public's perception of the value of gold. Gold in and of itself is basically useless (as opposed to silver and platinum which have MANY industrial uses), so the public's perception of its value is the primary reason for it having its current price. If the public accepts 2k gold jewelry as just as good as the other stuff, that makes my 24k gold bullion less valuable in the eyes of a big segment of the population. Can the investor market on its own maintain the impression of the high value of gold?
The only thing it really does is bring the price point down (though profits up) for "gold" jewelry. ie, low end consumer sales.
I think it could be bigger than that. Right now gold is valuable in jewelry because its viewed as superior in performance like not tarnishing. If in the future "gold" corrodes, I do think it would lower the value of the brand name of the metal, lowering overall demand. I would go the other way with it, not allowing this and doing away with 10 karat as well. I always thought 10 karat hurts the brand of gold already. It doesn't really look like gold at all.