This diffuser necklace has a black lava bead to hold your essential oils. On each side of the lava bead is a light blue crystal. The beads are attached to a high quality silver plated chain and is about 16 inches long. There is an additional 2 inch extender chain making the necklace wearable up to 18 inches long. When using essential oils with jewelry, please keep oils on diffuser beads only (lava or wood). The other elements of your diffuser jewelry are not intended to be used with oil. Please let the oil dry on the bead before wearing to prevent staining of your clothes or skin. Also, be aware of which oils you are using as the colors of some oils may discolor or stain your diffuser bead. If the diffuser bead develops a film, rinse in warm/hot water, do not soak. As with all my jewelry, due to conditions out of my control (climate, skin chemistry, etc.), I cannot make a guarantee on the longevity of your piece, however, I do my best to use high quality materials in hopes of a long life of your piece! Enjoy!