What is the most expensive diamond in the world?

Answer 1

Your question assumes that a diamond has changed hands for money. Many important diamonds, however, have never been sold, but have been owned based on the stone being a spoil of war or a gift to royalty.

The 'most expensive diamond' may be in regal crown jewels owned by a nation state. The British and Thai crown jewels are examples of magnificent diamonds held this way. Because they have not changed hands for money, there are essentially and otherwise priceless.

There are, however, a few examples of expensive diamonds, some with their record per-carat prices:

• The world's most expensive diamond -- 35.56 carat Whittlesbach blue -- sold for $24.3 million, beating a previous record of $16.5 million for a 100-carat diamond in 1995.
• The DeBeers Millennium Star Diamond
• The Taylor-Burton Diamond
• The Centenary
• Cullinan (never sold, gifted to the British Crown)
• Hope Diamond

• A 7.03 blue diamond sold for £6m ($9.5 million) in March 2009 in Geneva.
• Chopard blue diamond ring for 16,260,000 dollars. It has a 9-carat blue diamond, more white diamonds, and a 18k white gold setting. (In general, blue diamonds are the among rarest and most expensive diamonds in the world.)

Answer 2

The most expensive diamond in the world is the Pink Star diamond, which sold for $71.2 million in 2017. It is a 59.60-carat pink diamond renowned for its stunning color and clarity.