This 3.0 MM Silky Herringbone Link Chain Necklace is 10K Yellow Gold. Approximate item weight is 5.07 grams. Length is 18 inches. Width is 3 MM. Lobster clasp type. Caring for Your Gold Jewelry: to keep gold shining and scratch-free, avoid contact with chlorine and other harsh chemicals. Do not wear jewelry during rough work and be sure to store it in a fabric jewelry box or pouch. To clean gold jewelry, use warm water, a mild soap, and a soft-bristled brush, if needed.