Undiluted liver of sulfur is used to oxidize or 'black' silver.
Dip your jewelery for a few seconds in a solution of hot water (+ -80 ° C) with a few drops of liver of sulfur. Rinse your work well under the tap. Sand the high parts clear with a sanding pad.
Possibly fix with wax or varnish
Note: Efficacy decreases due to the influence of daylight. Therefore keep your liver of sulfur on a dark one. Place.
After blacking, neutralize your jewelry with baking soda.