DiamondBuzz
GIA Studies Unusual ‘Mottled’ Pink Diamond Formed Through Multiple Treatments
Analysis reveals how HPHT, irradiation and heat transformed a brown diamond into a fancy pink stone with a rare visual pattern
The Gemological Institute of America (GIA) has examined a rare pink diamond displaying an unusual mottled appearance, shedding light on how a combination of advanced treatments can influence both colour and visual texture.
The 1.10-carat round diamond, submitted to GIA’s New York laboratory, was graded as fancy deep brownish orangey pink. According to findings published in the fall issue of GIA’s Gems & Gemology journal, the stone stood out due to its patchy, mottled look—an uncommon feature in treated pink diamonds.
GIA’s analysis revealed that the diamond had undergone multiple enhancement processes, including High Pressure-High Temperature (HPHT) annealing, laboratory irradiation, and subsequent moderate heating. These treatments worked together to create nitrogen-vacancy (NV) centres within the stone, which are responsible for producing the pink colour. Prior to treatment, the diamond was originally brown.
Microscopic examination showed that the mottled pattern extended from shallow depths all the way to the polished surface. Further testing using visible and near-infrared (Vis-NIR) spectroscopy identified features consistent with irradiation and heat treatment.
GIA noted that the distinctive mottled appearance likely resulted from an uneven distribution of NV centres, influenced by the diamond’s nitrogen aggregates. While detailed mapping was not conducted to confirm this theory, the findings provide valuable insight into how complex treatment pathways can create unexpected visual effects in coloured diamonds.
Appoinment
De Beers Names Mallikarjuna Reddy Yarabolu as MD of Forevermark India
Appointment signals accelerated retail expansion as India emerges as a key growth market for natural diamond jewellery
De Beers Group has appointed Mallikarjuna Reddy Yarabolu as Managing Director of Forevermark India, effective January 2026, reinforcing its strategy to expand the brand’s footprint in one of the world’s fastest-growing natural diamond jewellery markets.
Mallikarjuna brings over 20 years of leadership experience spanning fashion, luxury, FMCG and organised retail. He most recently served as Chief Revenue Officer at Arvind Fashions Limited, where he drove sales and revenue strategies for leading brands such as U.S. Polo Assn., Arrow and Flying Machine. Announcing his departure on LinkedIn, he credited the leadership team for the opportunity to help stabilise and transform the business.
Earlier, he spent six years at Nestlé India, heading food service and retail formats including Maggi Hotspots, KitKat Break Zones, Milk Booths and Nescafé kiosks, managing a nationwide network of over 750 outlets. His career also includes senior roles at Aditya Birla Fashion and Retail Ltd. (Peter England), Walmart India and Godrej Agrovet.
The appointment comes as De Beers scales Forevermark’s presence in India, now the world’s second-largest market for natural diamond jewellery. Having transitioned from a loose diamond offering to a branded jewellery retail model, Forevermark plans to expand to 100 outlets by 2030.
With rising consumer incomes, increasing premiumisation and rapid growth of organised retail, India is expected to play a pivotal role in the future of natural diamonds. Yarabolu’s expertise in channel expansion and retail-led growth is set to support Forevermark’s next phase of growth in the country.
De Beers Names Mallikarjuna Reddy Yarabolu as MD of Forevermark India
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