Lapis Lazuli and authentic Silver-plated Necklace With Sapphires

Lapis Lazuli and lab corundum sapphires(no way to test sapphires). I tested the stones with acetone and no color came off so it is not dyed rocks. It does stay cold when I hold it for a bit but I am very cold natured. I don't know that this is the best of quality but I do think perhaps it is lapis as it passed both those test. There are some calcium color spots and fools gold specs as expected. I purchased the necklace from India many years ago. It is not authentic stamped anywhere. The necklace from fixed tip to end of chain is 9inches. One side chain is 4 inches and the other is 6. I have priced it a just a pretty necklace as there is no other way to test it. It does tarnish a bit so it is at least silver-plate. Never worn. I have not polished it but I will upon request