Any porous or organic surface exposed to prolonged periods of moisture is subject to developing mold. Organic or natural materials create a conducive environment for mold growth when wet. A jewelry box made with natural materials, such as wood, fabric or velvet, is a prime candidate for mold growth under the right conditions. To get rid of the musty odor inside your jewelry box, you must get rid of the mold spores, too.
Lay a towel in a sunny location outdoors or by a window. Set the jewelry box on the towel and prop it open.
Leave the jewelry box open and in the sun for at least 60 minutes. The sun kills any mold or mildew present while the fresh air helps to deodorize the box.
Moisten a clean sponge with undiluted white vinegar. Squeeze out excess moisture.
Sponge the interior and exterior of the jewelry box with the vinegar to kill any remaining mildew spores and remove the stains. Rinse the sponge as needed. Apply more vinegar and continue until the materials on the jewelry box have been cleaned.
Dampen a cotton ball with one or two drops of vanilla extract. Place the cotton ball inside the jewelry box and close the lid. Leave the cotton ball inside the box for 24 hours to remove any remaining musty smell.