Sure, when I check the bottom there was gold residue in the form of black specks and gold film in very few places, but the liquid went deep ruby red.
How much gold do you think you lost to the pot? If you can see it, its not insignificant.
There were about a dozen minute black specks, and on two-three patches 2-3 mm in diameter you could see a slight golden discoloration - approx area max 20 mm2.
Gold leaf for outdoor use weighs about 20 grams/1000 leaves. 1 leaf = 20 mg. Size 85x85 mm = 7225 mm2. Weight per mm2 approx 3 ug.
If you use gold leaf on something, you can' t miss it - it is gilded. The almost invisible discoloration in the SS pot was much less, almost an imperceptible golden tinge, see through.
For that particular batch I used 2 liters of DW and aimed for 40 PPM = 80 mg gold. That is 28900 mm2 when converted to gold leaf. If I had a FULLY gold leaf gilded spot of 20 mm2, I would have lost less than a 1/1000th of the gold.
I guess my loss on the spots was much less than that, but there was likely also reduced gold all over the pot but invisible. Gold leaf is approx 400 atoms thick, so when does it become invisible to the naked eye? Who knows... one thing is for sure - if 10% was lost the whole pot would have been quite golden. Electroplating (I guess this is one of your areas of expertise Kephra) is probably 10 atoms thick, and quite visible.
I think an insignificant amount of gold is lost if one is quick in making it in a metal container. I base this on the following:
1. Observation from my own experiments - same color and depth as colloidal gold made in glass container.
2. The above calculations/estimates.
3. The probability of getting more than 1% of the liquid/gold ions in contact with the SS surface in 30 seconds.
/J