Vintage 14k white gold Bismark chain with afixxed 1 karat cluster diamond heart

Rare vintage Bismark chain 14k white gold necklace with afixxed tested 1 karat of cluster diamond pendant weighing 8.38g and 18 in long, 4mm wide chain. Cannot find anything like it the bath's in the inside of the heart are hard to read even with a jewelers scope but there is a © marking after the 14k on the back of the heart. Crab clasp with making on every end of the piece, behind the heart, and in the crab moveable part that opens up. So it's marked with 14k in 4 different places on the crab cluster hinge it says 858. The letters after the copyright symbol look like ZRW but I'm not 100% sure.