A blue connector means you're looking at single-mode fiber with a UPC (Ultra Physical Contact) polish. UPC connectors have a flat endface and offer low insertion loss and back reflection. There are six fundamental colors in the visible spectrum – These are red, orange, yellow, green, blue, and violet. When we see a rainbow, we are seeing these principal spectral colors and from these colors come all other colors that we see with our eyes. The colors typically follow a color scheme established by industry. In fiber communications, the color of the fiber is not only an eyes-only indicator—it is actually used for determining the quantity, type of the fiber, and use of the fiber. Every fiber is color-coded, and this is a very crucial detail in the installation process, maintenance procedure, and. Fiber optic color coding refers to the color coding system used when manufacturing and installing fiber optic cables. The primary purpose of fiber optic color coding is to identify. Have you ever noticed that fiber optic cables in network closets or running through buildings are typically yellow, orange, and light green? These colors aren't random; they tend to represent different types of fiber. Without industry standards, building a fiber optic network would be a mess.