Vintage 14K gold filled necklace with natural picture agate stone

Vintage filigree pendant with unique natural picture agate stone. On a vintage link chain necklace that is stamped ECCO GF. In excellent condition. ECCO is a known jewelry maker, and GF stands for gold filled. Back then, mostly 14 karat and sometimes 12 karat gold was used for filling. This necklace looks like 14K GF because of the color of the filling. 16" long chain, 1.5" long pendant (with bail). Note: only the chain is marked, so not sure if the pendant is gold filled as well. Regardless, they match in color and look great together. Vintage gold filled jewelry is considered valuable and collectible as it is well made and also contains quite a bit of real gold.