Primary Test: Natural lapis lazuli is often dyed to enhance the blue color. The problem is the dye makes the color too uniform and covers up the often seen natural features of gold pyrite and white calcite. By lightly swabbing the stone with acetone or fingernail polish remover the dye will usually be easy to identify as it will come off on the cotton swab. Natural lapis lazuli is seen below with the mottled color including white calcite and gold pyrite. With dyed material the color is more uniform without noticeable variations.
Secondary Tests: None
Repair and Setting: This treated lapis lazuli is dyed to improve color. Any cleaning solution will remove the dye and cause the stone to significantly alter in color.