My favorite color is blue, I love all shades of it, do you like blue?
Blue is one of my favorite colors too, I like how it falls between violet and green in the visible light spectrum.
In the Middle Ages, European artists used it in the windows of Cathedrals
Wow that's really neat, I like how some shades of blue contain other colors, like how azure contains some green in it.
Blue became a popular color for military and police uniforms as well as business suits
That's true I definitely think of police uniforms when I think of blue. I read that Chinese artists used cobalt blue for porcelain in the 8th century, how cool.
Sometimes the color blue is associated with sadness, like a blue christmas
Blue really does have so many uses, it's even used as a reference to states that predominantly choose candidates from the Democratic Party even.
Yes and blue is associated with being a masculine color, blue for boys pink for girls
Color psychology
"color psychology"' is the study of hues as a determinant of human behavior. Color influences perceptions that are not obvious, such as the taste of food. Colors can also enhance the effectiveness of placebos. For example, red or orange pills are generally used as stimulants. Color can indeed influence a person; however, it is important to remember that these effects differ between people. Factors such as gender, age, and culture can influence how an individual perceives color. For instance, heterosexual men
worn by most national and corporate leaders. 
In science.
In science Optics.
Violet is at one end of the spectrum of visible light, between blue and the invisible ultraviolet. It has the shortest wavelength of all the visible colors. It is the color the eye sees looking at light with a wavelength of between 380 and 450 nanometers.
In the traditional color wheel used by painters, violet and purple lie between red and blue. Violet is inclined toward blue, while purple is inclined toward red.