"...The Queen of Heaven herself has granted an especial efficacy to this mode of supplication, for it was by her command and counsel that the devotion was begun and spread abroad by the holy Patriarch Dominic as a most potent weapon against the enemies of the faith at an epoch not, indeed, unlike our own, of great danger to our holy religion."
OCTOBRI MENSE ENCYCLICAL OF POPE LEO XIII ON THE ROSARY
Highest Heaven "is the abode of God. It is a realm of gold or purest light. Often represented as a Mandorla (or aureole) in which the Divinity is depicted."
You see it used in religious art often and in various ways.
Highest Heaven "is often separated from the angelic heaven by a border of clouds, or cherubs or rays of light. The Lamb of God, our Lord Jesus Christ, or simply an emblem representing God is placed here. Sometimes just the hands of God are shown to suggest His command or His blessing." Gloria Thomas
The Orb surmounted with a Cross means that the Christian Religion is for all and it indicates that Christ is the ruler of the World and savor of All. Sometimes written under it written (traditionally in Latin) is the quote: "The Cross stands while the world revolves." link
"By standardizing liturgical color codes
in the 16th century, reserving blue for the Virgin Mary,
Pope Pius V bestowed even more prestige upon the color."
From a short blog on the color Lapis Lazuli