Diamond market: December 2025 update

Welcome to our monthly column dedicated to the diamond market. Each month, we analyze the key global trends, the most significant events, and the dynamics shaping demand, prices, and commercial strategies. Drawing on authoritative sources such as Rapaport News, IDEX, and other specialized industry channels, we provide a consistently up-to-date, accurate, and reliable overview.

General trend

December 2025 was a month of relative stability for the diamond market, though with increasingly clear differences among the various categories of stones.

In the United States, holiday purchases were concentrated mainly on diamonds of 1.20 carats and above, with a preference for elongated fancy cuts. Overall sentiment remained positive, even as retailers continued to act cautiously, keeping inventories lean. Meanwhile, lab-grown diamonds continued to expand their presence in the fashion jewelry segment.

In Asia, the situation remains more complex. In India, both exports and domestic demand slowed, partly due to U.S. tariffs. At the same time, concerns are growing over the rise of lab-grown diamonds, reinforced by the launch of a new collection by Titan Company, one of the country’s leading jewelry groups. In China, demand for natural diamonds remains subdued.

In Europe, the market continues to be shaped by more selective purchasing decisions, with wealthier clients favoring certified diamonds with transparent provenance. The sector, however, is still grappling with geopolitical uncertainties and challenges related to international trade, which weigh most heavily on smaller stones.

The overall picture remains clear: smaller diamonds, especially those below 1.20 carats, are facing greater difficulty, while higher-quality stones tend to hold their value more effectively. In this environment, the growing demand for certified traceability and the interest in distinctive cuts underscore a steadily strengthening focus on uniqueness and genuine value.

Price trends

In December, the market confirmed the structural divergence already observed in previous months: further declines in the lower categories and relative stability in the premium segments.

Rapaport’s RapNet Diamond Index (RAPI™) for 1-carat round diamonds (D–H, IF–VS2) fell by 2.3%, continuing the negative trend seen throughout the year. Lower categories experienced sharper declines, with 0.30-carat diamonds down 9.3% and 0.50-carat stones down 6.4%, largely reflecting pressure from the Indian market. By contrast, 3-carat diamonds posted a slight increase of 0.3%, further reinforcing the picture of market polarization.

The IDEX Polished Price Index recorded a decline of 1.35%, less pronounced than November’s drop (–1.72%), suggesting a slight slowdown in the pace of the downturn. On an annual basis, however, the figure remains significant: over the course of 2025, the index lost 10.9% of its value—a substantial contraction, albeit smaller than those recorded in previous years. These declines stem from weak demand for mid- to lower-quality diamonds, cautious inventory management by market participants, and growing competition from lab-grown diamonds.

In summary, December presents the picture of a market that many operators describe as being in a phase of a “controlled and prolonged landing” rather than a steep freefall. Quality, rarity, and traceability remain the key factors supporting value, while lower-end segments continue to face structural pressure, reflecting a profound shift in global demand.

Reflections from the diamond world

The “Desert Rose”: the value of pink diamonds at international auctions

Among the December auction highlights, one of the most notable events took place in Abu Dhabi, where Sotheby’s presented a gemstone of extraordinary rarity: the Desert Rose, a 31.68-carat pear-shaped diamond distinguished by an intense orange-pink color and VVS1 clarity. The stone sold for $8.8 million, exceeding initial estimates and confirming one of the key dynamics of 2025: in a climate of global economic uncertainty, collectors increasingly gravitate toward rare and authentic assets as stores of value.

The Desert Rose result underscores how diamonds of exceptional color continue to demonstrate resilience—and in many cases appreciation—even during periods of broader market weakness. Demand from high-net-worth clients remains strongly focused on authenticity and uniqueness, qualities that neither technological innovation nor lab-grown diamonds can fully replicate. Natural pink diamonds, in particular, remain among the most sought-after. The closure of Australia’s Argyle mine in 2020, historically the source of around 90% of the world’s pink diamonds, has further increased the rarity and desirability of these gems among international collectors.

The Louvre theft: vulnerability and security in the luxury market

In December, the worlds of art and high jewelry were shaken by developments in one of the most audacious thefts of recent years. On October 19, 2025, a group of thieves disguised as construction workers managed to gain access to the Louvre’s famed Galerie d’Apollon (the world’s most visited museum), using a forklift to reach a second-floor window. In less than ten minutes, nine jewels of exceptional value were stolen, with an estimated total worth close to €90 million, including historic tiaras, sapphire necklaces, and highly significant colored diamond pieces.

On December 23, while the investigation was still ongoing, the museum installed new security bars on the window used for the break-in. The incident nevertheless exposed significant shortcomings in the institution’s security systems: a subsequent inspection revealed that approximately 35% of the Denon Wing, where the jewels were housed, was not covered by video surveillance. Although four suspects have been arrested, the theft remains a clear reminder that even the most prestigious cultural institutions are not immune to risk.

The episode invites a broader reflection: in an era of digital traceability, advanced certification, and blockchain technology, how can assets of such extraordinary value still remain vulnerable? This question extends beyond museum security, touching on how the luxury market will approach protection and the preservation of value in the future.

Conclusions

December 2025 closes with a diamond market still in transition and an increasingly evident polarization: more common stones continue to lose value, while rare gems show greater resilience and appeal among international collectors.

Looking ahead to 2026, the outlook remains complex but offers room for opportunity.

For collectors, current price levels (especially for high-quality stones) make it possible to access extraordinary gems at valuations that would have been difficult to reach in the past.

For diamond owners, this moment represents a strategic opportunity. A professional appraisal makes it possible to understand the true potential of ones assets, whether the intention is to preserve them as a generational investment or to consider liquidation when market conditions are favorable.

Auctentic supports those seeking to navigate this landscape with discretion, expertise, and transparency. A professional valuation is the first step toward turning assets into awareness and awareness into sound decisions. Contact our gemologists today to discover the true value of your gemstones, fine jewelry, or high-end watches.