Abstract The paper describes and analyzes the full presence of blue in the Old Testament – in Hebrew and translations. The interdisciplinary approach includes the treatment of color as a cultural unit according to of Eco’s idea, lexical and contextual semantics, distinguishing visual and verbal color languages. The interface between verbal and visual color language is the prototype. Prototypes are universal natural visual objects – sky, sea, fire, blood, the sun at noon, all plants, light, milk, snow, darkness, and coal and have evolved into cultural units (Eco 1996 [1985]) in all cultures and languages. Basic Color Terms (BCT – blue ), Prototype Terms (PT – sky and sea ), Rivals Terms of prototypes (RT – sapphire, blue skins ), Terms for Basic Features of the Prototypes (TBFP – breadth, infinite, boundless ) are examined. Translation is a criterion for semiotic value, cultural and linguistic context. Norm of Test of Free Word-Associations is a source of non-color (secondary) meanings of verbal colors. Test results allow us to flesh out the hidden links ‘prototype color ─ most typical feature of the prototype ─ secondary meanings of color’ in text and visual culture. The secondary cultural meanings of BCTs and RTs are specified in color compounds. The color blue tehèlet is used in most cases in synergy (not in opposition) with the other three colors in a tetrad: purple argamàn─ scarlet tolàat shanì─ linen shesh. Analysis on the synergic relations is performed. The same applies to duads blue-linen, blue-purple, blue skins-scarlet, blue skins-red skins. Color compounds are elements of the Priestly Code, therefore a hypothesis on compounds at semiotic axes is developed. The PT sky is involved in religious heritage. Themes as Hebrew substitute shamàim for the Tetragrammaton, the Hierarchy of heavens complete the areas of cultural unit blue in the Old Testament.