Let's say I buy a barbecue grill, is there a material testing kit that I can buy that'll allow me to find out what metal the grill is made from and if it were galvanized or cured in a particular substance?
The test kit is a magnet and horse- sense. If magnetic = steel (most likely) , shiny and magnetic= chrome stainless. Non-magnetic and shiny = austenitic stainless aka 18-8 . Non-magnetic and silver grey but not shiny and feels cold and relatively light = aluminum ( likely ). Magnetic and silver grey = galvanized steel , a dumb material choice for a grill. How do you "cure" a metal ?
You can buy a device that tells you what elements are in a lump of something. This is gross overkill for a barbecue grill. As others have said, a magnet and a little common sense goes a long way for that.
However, the device I'm talking about is a X-ray spectrometer. These are available in a handheld "gun" configuration, as one example. You point the device at your unknown lump of stuff and pull the trigger. It blasts the lump with x-rays with controlled wavelengths, and looks at the resulting emissions.
Basically, bombarding with high enough energy photons makes pretty much everything act like a phosphor. The high energy photons cause electrons to move to higher states. The photons emitted by falling back to the lower states is distinctive of the particular element. Collect enough of these re-emission photons to get a nice spectrum, and you can tell what elements are in the lump of stuff to surprising accuracy.
One company that makes such devices is Thermo Fisher. Uses include assaying of minerals, looking for lead in paint on old houses, and lead and other bad things in toys being imported. These devices have tables of common alloys built in to their firmware. They not only tell you directly that your lump is stainless steel, but what type.
While such a thing would definitively answer your question, it would be gross overkill since its cost is many times that of a new barbecue grill. If you are deciding which area is best to mine for gold though, the cost is likely well worth it.
weldinghandbook.com has an excelent article covering this, which I will not repeat in full!
In summary - check first if your material is magnetic, and then follow one of these three processes: