How To re-oxidize your jewelry at home:
These instructions are for sterling silver and will work with jewelry set with stones.
Liver of Sulfur
Mug or Pyrex Bowl
Step 1: The process works best with clean jewelry. Wash in warm soapy water. If Set with an Ethiopian Opal, Omit the soap. If there are no stones present, you may use a steam cleaner or ultrasonic to clean the jewelry. Otherwise, just use an old toothbrush with the warm soapy water and then rinse and alloy to air dry.
Step 2: Heat up some water. About 1 cup in the microwave for 30 seconds is hot enough. It does not need to boil, just hot to the touch but not so hot it burns you. This is more for the safety of any sensitive stone that may be present. If no stones are present, then use very hot water for faster results.
Step 3: Add a bean size chunk of the sulfur to the hot water. Stir with a disposable coffee stirrer or wooden skewer (something you'll throw away). The Water will turn yellow.
Step 4: Dunk the jewelry in the water. Start with quick 1 second dunks and evaluate the color change after each dunk. generally each dunk will yield a darker and darker finish until it is completely black. If you want a full black tone, then just leave it in about 10-20 seconds is all you need. When you remove it, it should be completely black.
If the jewelry was polished when dunked, the black will also be more polished as well. If it was a satin or brushed finish, it will yield more of a flat black.
These advanced instructions are for adding a little more color to the oxidizing process.
AC Adaptor (for stereo, printer, etc..)
copper alligator clips with insulated color coded handles (Red and Black)
Positive = Red, or smooth
negative wire = Black or Ridged Wire
Step 1: Cut the end off the cord (The part that plugs into an appliance). Separate the two wires for about 3 inches. Strip the ends. Connect the positive wire (red) to the Red alligator Clip. Tape the connection or use a wire nut. Repeat with the negative (Black) wire.
Step 3: Follow Steps 1-3 as above, but only use room temperature (luke) warm water.
Step 4. Connect the Positive clamp to the jewelry. Plug in the adaptor, while making sure to not touch the copper leads to each other (sparks will result). Submerge both the negative and positive leads into the oxidizer making sure they don't touch. Remove after 3-4 seconds to test for color. The jewelry should take on a greenish-blue color. Repeat until you achieve the desired color. Warning, The oxidizer will eventually turn the piece grey, so leaving it in will not result in a richer green/blue.
If the color seems to concentrate around the clamp, then simply relocate the clap to another part of the jewelry and keep dunking.
This is very much a slimed down version of how to do this process, and in my shop I use some slightly more advanced tools and procedures, but this is meant to get results for $10 or less. I cannot guarantee that you'll succeed or get the results that you want, but for the DIY'er this should be a fun learning experience and may even yield just want you wanted!
Failure is always an option! If you over do it, or don't get the color you wanted, then you can always wait until next time and then try again (after the oxidization has worn off again). If you cant wait that long, there are several Deoxidizers on the market that will strip off the oxidized layer.