Diamond Prices Finish 2025 Deep in the Red, Smaller Stones Hit Hardest

Diamond prices declined again in December 2025, extending a prolonged downturn that pushed full-year losses to as much as 26% for certain categories, according to data from industry agency Rapaport.

The renewed weakness highlights persistent demand challenges in the global diamond market as the sector enters 2026 with elevated uncertainty.

December Declines Accelerate

The RapNet Diamond Index (RAPI) shows that prices for smaller diamonds fell sharply in December. The index for 0.3-carat diamonds dropped 9.3% month-over-month, while 0.5-carat diamonds declined 6.4%.

By contrast, prices for larger stones proved more resilient. The index for 3-carat diamonds edged up 0.3% in December, indicating relative stability at the higher end of the market.

Full-Year Performance in 2025

For the full year, declines were broad-based but uneven across segments:

• 0.3-carat diamonds: −20.3% in 2025
• 0.5-carat diamonds: −26.0% in 2025
• 1-carat diamonds: −9.9% year-over-year
• 3-carat diamonds: −0.3% in 2025

The 1-carat diamond index declined 2.3% in December, leaving prices 9.9% below year-ago levels and 6.5% lower than at the end of 2025.

Diverging Trends Across the Market

According to Rapaport, market dynamics diverged sharply by stone size in December. While prices for polished diamonds weighing more than one carat remained broadly stable, smaller stones experienced intensified selling pressure.

The agency noted that the diamond industry entered 2026 facing the same headwinds that dominated much of the previous year, including weak consumer demand, inventory imbalances, and cautious purchasing behavior across key markets.

The continued softness in prices suggests that a clear recovery in the diamond market remains elusive. With smaller stones under sustained pressure and larger diamonds showing only limited resilience, the industry faces a challenging start to 2026.

Market participants will be watching closely for signs of stabilization in demand and inventory levels as the year unfolds.