Blue Sapphire and Heart Chain Necklace15. 5" long, 2" chain, 17. 5" total length genuine blue sapphire gemstone Chain is 18 kt gold fill "Gold filled" comprises a solid layer of gold (14K) permanently bonded to a base metal, such as brass. The minimum layer of gold must equal at least 1 20th of the weight of the total item. It is very hard wearing and under normal wear the gold will not peel or flake, unlike gold plate, and is commonly used as a more economical alternative to pure gold.