Thanks everyone! I knew I was going to get the feedback that pointed me in the right direction!
I really like these circuits:
The first circuit pictured links to an explanation of the circuit, but it's in Danish and didn't translate well enough for me to understand. But it looks like it uses an op amp, capacitors, and a transistor to create an oscillation through the coil that would produce a low radio frequency. How low would the frequency be? I'm sure you can calculate it somehow based on the values of the components but I have no idea how to do that.
If you click the link on the second circuit, it leads to a page that explains the circuit in good detail, but you'll notice the picture here has an added mosfet before output to the arduino. I think the purpose of the mosfet is to amplify the small current signal that comes from a disturbance (eddy currents skimming the surface of a conductive material silverware) in the electromagnetic field. PLEASE CORRECT ME IF I AM WRONG OR MISSING SOMETHING
I am thinking I will build the second circuit and experiment with different coil sizes and shapes, AND a variable capacitor for c1. I'll experiment and hopefully I can find the right combo that will give the arduino the best possible picture of what silverware will register as.
Erdin:
I think it would be possible to let the Arduino create a pulse for the coil, and detect the received pulse length. But I have not seen such a circuit yet.
I don't understand how the arduino is put together or how it works in detail, or what could really even be done with it, but that seems possible. Some one use your huge brain to figure this one out! haha