Hi SB, Well I use a 10x jewelers Loupe and have a look at the fine particles, you will know the gold when you see it, it will always look gold no matter what the direction of the light is coming from. Pyrites etc will change from highly reflective from one direction but look like a piece of gravel at another..
Smelting would be an activity that you could do if you had enough to make a button with, at least a gram. that would appear like a lot of fine gold, you would also have problem of potentially blowing it all out of the crucible if you went about it the wrong way...
I will try and take some pics or a vid of how I separate super fine gold mixed with other minerals and gravels when I get some, hopefully over Easter.
Patience is the key when working with micro gold.
Cheers, Tone