The national colours of Israel are azure and white as seen on the flag of Israel.
[1] Blue and white are perceived as patriotic colours in the State of Israel and the Jewish world.
Blue and white are used in flags, symbols, etc.
Eg: Blue-White (Blau-Weiss)[2] Zionist youth moment in Germany and Blue and white (He) patriotic song.
[3] Book of Numbers mentions in 15:38, it states that the Israelites were commanded to put fringes on the corners of their garments, and to put a cord of blue border upon these fringes.