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Understanding Indoor Fiber Optic Cable Color Schemes

Understanding Indoor Fiber Optic Cable Color Schemes

Fiber optics are common in many networks, and they’re essential to provide enough bandwidth and capability in modern digital communication. If you work in networking, you have to learn at least the basics of fiber optics.

To start today’s lesson, we can remember that fiber optics come in two modes: single and multi. Single-mode fiber does better with very long-distance communication while multimode fiber is capable of higher overall transmission rates.

Multimode fiber optics utilize a specific designation of OM1 through OM5 (with higher numbers representing faster cables). Meanwhile, single-mode fiber uses OS1 and OS2.

With all of that covered, each type of cable has a color designation, so you can tell by looking at the outer jacket what kind of fiber optics are in use. Below, you’ll see a complete breakdown of these fiber cable jackets by their colors.


The first outer jacket color on the list is orange. Orange is used for both OM1 and OM2 cables. If you see orange, you know it’s one of the two, but you might not know which. You can tell the difference between OM1 and OM2 because it is usually printed on the cable.

All of that said, OM1 and OM2 are old. You won’t be installing them into new networks, but you might come across them in legacy networks.


Next up is aqua, which is the jacket color for both OM3 and OM4 (OM4 is sometimes violet, which is covered in the next section). OM3 is still on the older side of things as far as multimode fiber cables go, but you will see it used a lot more than 1 or 2. Some networks might do limited OM3 runs to save a little money here and there.

As for OM4, it’s pretty much your starting point for modern fiber optics. When it comes to distinguishing OM3 from OM4, the same rule as before applies; the designation is printed on the cable.


Sometimes, OM4 is colored violet instead of aqua. Violet is only used for OM4, so it’s very easy to tell what you have when your fiber jacket is violet. It’s worth noting that the jacket color is not a deep violet. It’s on the pinker end of the violet spectrum.

Lime Green

Moving on to lime green, this color designates OM5 fiber optics. This is premium multimode fiber. OM5 can reach data rates of 100 Gbps. It goes in top-of-the-line networks, and lime green is the only color used to designate OM5.


Yellow is the designation for single-mode fiber. There are two primary variations for single-mode: OS1 and OS2. The exact same yellow color is used for both. If you see yellow, you know instantly that you’re working with single-mode, but you don’t know which.

The same old rule comes up again. To tell between OS1 and OS2, check the print on the cable itself.


Last up is blue. Blue is not a super common color for fiber optics. It identifies polarization maintaining single-mode fiber. This is a specialized type of cable that polarizes the light in the cable and maintains that polarization.

It’s used in niche applications, and most networks don’t utilize blue fiber optics. But if we’re going through the colors, you might as well learn about blue.

Internal Color Sequence

That covers the external jacket colors, but fiber cables have internal components as well. Those are also color-coded, and they follow a specific pattern. There are 12 colors for the inner fibers, each in a specific part of the sequence. Those 12 colors are then repeated in the same sequence, but they have a stripe. Combined, the sequence utilizes 24 distinct color patterns:

  • Blue
  • Orange
  • Green
  • Brown
  • Slate
  • White
  • Red
  • Black
  • Yellow
  • Violet
  • Rose
  • Aqua
  • Blue with black stripe
  • Orange with black stripe
  • Green with black stripe
  • Brown with black stripe
  • Slate with black stripe
  • White with black stripe
  • Red with black stripe
  • Black with yellow stripe
  • Yellow with black stripe
  • Violet with black stripe
  • Rose with black stripe
  • Aqua with black stripe

That covers all of the different fiber cables and colors in modern use. Some discontinued colors, like gray, were excluded because you won’t see them at all. With this simple guide, you can get a clear idea of what kinds of fiber optics are at play at a single glance.

Additional Learning Center Resources