First we start with an electrolytic refining cell. This kind of cell is generally used to refine silver, copper, and gold. But during the refining process silver and copper are capable of forming crystals. Gold will not crystallize it only plates out, which works great for refining but isn’t nearly as beautiful.
Next we create our solution. When growing silver crystals we take and dissolve pure silver granules into nitric acid and purified water using a boiling process. The process is complete when the granules are dissolved and the PH has risen from a 0 to a PH of 4. This solution is called an electrolyte solution and contains approximately 20 oz of silver per gallon.
Now we take our electrolyte solution and pour it into the cell. A cell should be anywhere from two to four gallons. Then we take and submerge our plates. One plate is at least 92% pure silver and the other is stainless steel. Once the plates are submerged and secured we hook up the electricity. We attach the positive lead to the silver plate (anode) and the negative lead to the steel plate (cathode). Then using a DC trickle charge we run approximately one and a half volts through the cell.
As the silver plate is dissolving it gives off a black sludge so a fine cloth bag is placed around the plate to collect the sludge for easier cleaning. This sludge contains all of the impurities from the silver plate. In this process an impurity is anything that isn’t silver such as gold, tin, zinc, and lead, but not copper. Copper is dissolved into the solution. So when the solution turns a dark blue color it is time to discard it, but not before the silver is removed to be used again.
It takes about 24 hours for average crystals to form and three to four days for the bigger heavier ones. Once the crystals reach the desired size the plates are removed from the solution and the crystals are scraped off and cleaned with distilled water and allowed to air dry.
There are several factors that influence how a crystal will form. The amount of electricity running through the cell, the amount of silver in the solution, even the temperature (the crystals prefer the warmer temperatures).
The process for creating copper crystals is the same as with the silver, we simply switch out the silver and steel plates for copper ones and the silver granules with copper wire. And to create the copper crystals on the pennies we simply attach some copper pennies to one of the plates and watch them grow.
The above post is reprinted from Treehouse Silver