well its really depends on, really hard to tell at this stage due to i am not really sure about the chinese opal market. as i know, there are a few big opal produce companies in Australia, none of them are really big companies but they had the clients all over the world and make good sale all the year. as i know opal in africa, the quality is poor and after 5 years, it is easy to get break. if you really like that, you can add wechat on me which is frankzhang0320, i know one boss from opal produce company in Australia, can send the opal pic to you and give you the best price... by the way i am chinese australian. cheers
