Step 1: Buy or Borrow black or dark brown nail polish.
Step 2: Take a small amount and apply to a rag.
Step 3: Rub charm with rag containing small amount of nail polish. (See step 2)
Step 4: Let dry.
Step 5: Repeat steps 2-5 until desired effect is achieved.
(Apply the nail polish as thick as you would apply car wax. Don’t paint it.)