By Charlotte Reid 
A recent archaeological discovery and its sale clearly demonstrate how the same shade has fascinated experts and collectors for centuries. From ancient techniques to market trends, scientists and artists are united under a single influence.
Blue, a colour that has captivated scientists and artists alike, has become the star of two events linking European prehistory with contemporary art.
Christie’s auction house in Paris announced the sale of California (IKB 71), the largest blue monochrome painting by Yves Klein still in private hands, with an estimated value of over €16 million.
At the same time, a group of researchers from the UK discovered the oldest known use of blue pigment in Europe, dating back some 13,000 years, thereby rewriting the history of colour on the continent. Both news items reflected the enduring appeal and cultural significance of the colour blue, which has been present in the art market from prehistoric times to the present day.
The California (IKB 71) auction and its significance in the art market
The Paris auction house Christie’s has placed the painting ‘California (IKB 71)’ as the centrepiece of its ‘Avant-garde(s), including “Reflections on Italy”’ auction, scheduled for 23 October 2025.
The painting, measuring 196 x 421 cm and created by Yves Klein in 1961, is the artist’s largest monochrome work in a private collection to be offered at auction. The painting debuted at the Dwan Gallery in Los Angeles during the artist’s only stay in the United States, and was then exhibited at the Metropolitan Museum in New York from 2005 to 2008. After many years in a private collection, the painting returned to Paris for its first public auction.
Catherine Arnold, director of Christie’s post-war and contemporary European art department, called the work ‘a monochrome painting of colossal importance.’ The auction house, which has set three records for Klein’s works, expected this work, whose textures anticipated ‘Planetary Reliefs,’ to exceed €16 million.
The scale of California (IKB 71) was surpassed only by the murals Klein created for the Musiktheater im Revier in the UK, which are between five and seven metres long.
Blue in Yves Klein’s work and his innovative technique
The colour blue played a central role in Klein’s work, and he patented International Klein Blue (IKB) – a mixture of pigment and synthetic resin developed in collaboration with Edouard Adam. This formula preserved the intensity and brightness of the colour, preventing the resin from dulling the blue.