Klein produced a number of monochrome paintings before concentrating on a single colour, a particular shade of blue. He wanted to obtain a saturated and bright hue, without any alteration, that could be extra-dimensional and capable of representing all the primary elements of the universe, particularly the opposition of fire and water. “Blue is outside of any dimension, whereas other colours have one”: colour should inhabit real space, outside of and beyond the canvas. Klein sought a solvent capable of fixing the pure powder pigment to the support and patented the ultramarine shade with the name of International Klein Blue. His research on this subject reveals an interest in alchemical processes and certain scientific, philosophical and religious disciplines that influenced his art. In 1959, he shifted from monochrome to the use of a trilogy of colours consisting of blue, gold and pink. These three hues have a strongly symbolic content that allows the work to echo the immaterial and make the invisible visible: the artistic product is intimately bound to reality and nature, but at the same time contains the spirituality required to perceive the evanescent and immortal beyond. In harmony with the New Realism movement, of which Klein was one of the founders, in 1960, he developed a new form of appropriation of contemporary reality, which found expression in his art through the creation of plastic works. Portrait Relief of Arman and Portrait Relief of Claude Pascal come from this period of change and completion of his artistic development. Both portraits of his friends and associates conjure up images of plastic religious icons: from depictions of Christ, saints and martyrs to the funerary monuments inspired by classical and Roman art. The busts of the painter Arman and the composer Claude Pascale, made in bronze covered in blue pigment, indiscriminately highlight the characteristics and defects of their human bodies, from their facial features to their genitals. However, the earthly dimension is freed in the luminosity of gold, from which the figures stand out, intended by Klein as an allusion to the alchemical transmutation of matter and the attainment of infinity and eternity.