Check Kellyco's website. They have a gizmo that detects whatever you put in the chamber like diamonds, paper money, etc. It is even slightly radioactive. Check it out.
I don't think so. Most gems and stones are found with shifters.
And regular mining.I have found some jade sluicing. There are different gem camps you can go to,
buy a bucket of paydirt for $10-50, they will give you a shifter and water, you may find that nice piece worth thousands.Another fun hobby!!!!!!!!
RD