Editor’s Note
This article highlights a remarkable sale at Bonhams’ London Jewels Auction, where a Colombian emerald ring fetched nearly six times its high estimate. It underscores the continued strength and exceptional demand within the high-end jewelry market for rare and historically significant pieces.
A 10.37-carat ring featuring a Colombian emerald was sold for £597,300 (approximately 110 million yen*) at Bonhams’ ‘London Jewels Auction’ held in London on December 11, 2025. This amount significantly exceeded the pre-sale high estimate of £100,000, representing approximately six times the expected price.
In addition to the emerald, the same auction featured numerous historically significant jewelry pieces and rare colored diamonds that traded at high prices. Specifically, a 1935 Cartier necklace lavishly set with an approximately 11-carat Burmese ruby sold for around 34 million yen*, and a distinguished ‘transformable diamond tiara’ once owned by a former lady-in-waiting to Princess Margaret of the UK also recorded a high price of about 19 million yen*.
Furthermore, attention on colored diamonds was high, with a luxurious ring set with a rare fancy yellow diamond selling for approximately 14 million yen*, indicating strong global investment demand for gemstones.
*Exchange rates are approximate at the time of writing.
In tandem with this overseas market boom, consultations within Japan regarding gemstones other than diamonds (colored stones) such as emeralds, rubies, and sapphires are also on the rise. Particularly in the context of estate and asset organization, there are many requests for more advanced and specialized appraisals, with concerns such as “items being appraised cheaply without understanding their true value” and “wanting detailed evaluation of origin and quality.”
Among these, the “emerald,” which fetched the high price in this auction, is a gemstone more difficult to appraise than diamonds. Its value is determined by a combination of factors including “color,” “inclusions,” “origin,” and “cut quality,” meaning the knowledge and experience of the appraiser can significantly impact the final valuation amount.
In response to these global market trends and the growing domestic need for asset organization, “Omoio” is strengthening the following measures:
– Enhancing the appraisal system with specialist appraisers, including holders of GIA qualifications.
– Re-evaluating the assessment of “Brand × Antique” items.
To handle the multi-faceted and advanced judgment required for appraising gemstones, the store employs specialist appraisers who hold the “GIA-GG” qualification from GIA (Gemological Institute of America), an international authority in gemology. The system is designed to provide accurate market value and fair prices based on experience from over 30,000 purchase transactions.
Furthermore, for “brand antiques” like Cartier, which achieved high prices in this auction, an evaluation standard that adds the rarity, design, and historical background (added value) of the product itself will be applied, rather than relying solely on general precious metal weight-based appraisal.
