Both of the hearts are made of stainless steel and the center, smaller heart is rose gold plated. Stainless steel is hypoallergenic and will hold up to years of wear.This is the perfect gift and a unique way to carry your loved ones close to your heart, Always keep your loved ones close to your heart with my unspoken words memorial necklace. Every necklace can be filled with one funnel kits, You can access the compartment in the pendant through a small screw in the top.