I have instructions for how to do this yourself and also a video of what to expect. Enjoy!

Many common acids will dissolve common metals, but it can be challenging to remove noble metals and organic residues. This is where aqua regia and piranha solution come in handy. Aqua regia is useful for dissolving gold or platinum. Piranha solution is used to remove organics from the surface of gold or silicon. Both solutions are powerful and should be used with extreme care.

Aqua Regia
3 parts HCl (hydrochloric acid) to 1 part HNO₃ (nitric acid)

Mix aqua regia under a fume hood since the reaction of HCl and HNO₃ produces NOCl (nitrosyl chloride), Cl₂ (chlorine gas), and H₂O (water) .

Piranha Solution
5 parts H₂SO₄ (sulfuric acid) to 1 part H₂O₂ (hydrogen peroxide)

Add the peroxide to the acid, not the other way around. The reaction to produce piranha solution evolves heat, possibly boiling when the reactants are mixed.