Idex Research: 1-Carat Diamonds Lost 3.5 Times More Value Than 5-Carat Stones Over Five Years

Looking at the market over a five-year period removes the distortions created by the COVID-19 buying boom. During this period, 1-carat diamonds lost 47.5% of their value, compared with a decline of just 13.6% for 5-carat diamonds.

The 1-carat price index includes round diamonds weighing 1.00 to 1.49 carats, in the D-K color range and IF to I1 clarities. The 5-carat category includes round diamonds weighing 5.00 to 5.99 carats, in the D-J color range and IF to SI2 clarities.

A leading diamond manufacturer, who requested anonymity and specializes in high-value large stones, told Idex that 5 to 10-carat D/IF diamonds have remained relatively stable over the past five years. His estimate of a 10% to 12% decline in prices during this period closely matches the trend reflected in the Idex Price Index.

Another trader specializing in expensive goods, indicated that 5-carat stones experienced a slightly larger decline in value than 7- to 10-carat goods. According to his estimate, prices for 7 to 10-carat diamonds outperformed the 5-carat category by approximately 3% to 5% over the same period.

Smaller polished goods, including melee, full-cut, and goods ranging from 1/10 to 1/30 carat, have experienced an unprecedented decline over the past six months, with prices falling by 20% to 25%, and even more in certain categories.

However, rough diamond traders report a modest recovery in demand for smaller rough goods in recent weeks following the announcement by Angolan mining giant Endiama that it would reduce the supply of smaller rough diamonds to the market.