525 SAKI peacock iridescent necklace

525 SAKI brand black/peacock iridescent color stones irregular shapes- i've down a lot of research and these look like tahitian-like tonal value... in sun changes them from purple to greenish to blueish.. honestly i'm not sure what i have so if anyone has seen these before please let me know any information you may have that would be very helpful!!! i don't want to undervalue these beauties!!! SAKI and 525 sterling silver engraved on hardware.. gorgeous piece!!!!!