This is my set of steps:
First I do a fast "dirty" pan. Where I just dump my cons into my pan and do a really quick and dirty pan over a catch pan/tub. I tend to think that if I'm panning correctly that most large gold is going to make it to the bottom of the pan. This should eliminate any gold larger than the +20 mesh size (I have been fooled once!). So I don't generally think that I'm missing any gold nuggets that are larger than a 1/8" screen, but smaller than the 1/4" that my sluice classifies too.
I'll also hit that pile with a metal detector next time I go out since I'll have my MXT with me. While not the best detector on small gold, I do think it would be able to find a nugget in the -1/4" to + 1/8" size if it somehow didn't make it to the bottom of my quick and dirty pan. But I think any gold that size would have a hard time staying on top. Not that I've found anything that big yet! But I doubt I'm leaving any nuggets at the river in that gravel pile.
