Doublet Opals

I wanted to rent this place and sell the most faboulous jewels in the world for the local and int'l market. It is my first time to visit this store but not this branch the coz this one is closed I supposed. I was looking for a horseshoe diamond ring in yellow gold and white gold & I saw one I like from Gaisano for 36k pesos more or less. So when I window shop canvassing for better cheaper rings I can't resist to enter this store coz I saw one their window display an attractive matching set of jewelries featuring black opal & diamond mounted in white gold. I knew black opals are very rare & in fact I have never seen any jewelry store that sells them so I was curious & went inside for further inspection & the salesladies showed me the ring and earrings & instantly I knew they are doublet opals! Selling for 138k pesos! If they are solid opals it would have costs more! Maybe 300k to 500k coz there aren't any red play of colors just dark b...