UNMOUNTED OPAL 17.92克拉天然未經處理蛋白石 Certificate: Lotus, crystal opal, natural, 17.92cts, near colorless with low saturation and light tone, unheated/untreated; with note 'this gem displays a rare play-of-color effect when viewed in direct sunlight' (2214-6071, 22 February 2019) Footnotes: Please note that the report is over five years old and may require an update. 請注意上述證書發行達五年以上，或須更新 NO RESERVE 不設底價 CONDITION REPORT: Crystal Opal: The tapered tubular opal of pearly white colour with blue and yellow undertone, translucent. Very good play-of-colour: flashes and rainbow shades are even and well-distributed. Under 10x magnification, there are neatly arranged tiny blue silica across which produces the play-of-colour effect. Some internal minerals and inclusions can be observed, however not obvious to the unaided eyes. This condition report is provided for your convenience based on the opinion of our specialists. Bonhams is not responsible for any discrepancies between this information and other opinions. The condition of lots can vary widely and the nature of the lots sold means that they are unlikely to be in perfect condition. The dimensions and weights of diamonds and gemstones are approximated using measurements and given as a courtesy, please consider them as an estimation only. Please note additional images and videos are available upon request, kindly contact the jewellery department at jewellery.hk@bonhams.com Lot to be sold without reserve. For further information on this lot please visit Bonhams.com For further information about this lot please visit the lot listing