A variety of factors affects how colors look including:
When the gobo is printed on glass vs. paper
The medium the design is printed on has an effect on color. There are many types of paper but all paper is porous and will absorb some ink. Printing on a gloss paper vs. an uncoated paper will change the color. Glass does not absorb ink and the translucent nature of glass has an impact on the color.
How the color is created.
There are two different ways to create color and both produce slightly different colors.
CMYK is a subtractive process. It is how colors of paint and ink are created. It starts with nothing (white paper), as more colors are added the color eventually turns black. The acronym “CMYK” represents the standard color inks use to create color cyan, magenta, yellow and black.
RGB is an additive process. It is how colors are created with light. It starts with black (darkness), as more colors of the light spectrum are added the color eventually turns white (a regular light bulb). The acronym “RGB” represents the colors of the light spectrum used to create color Red, Green, Blue.
Computer monitors, cameras and TVs use RGB to display color. When you are print, CMYK is used. So when a graphic is shown on your monitor, it is only an approximation of color since it is actually being displayed in RGB. In addition, not all colors are easily reproduced in CMYK. Some very bright colors like turquoise are not possible without special inks.
How your monitor/printer is calibrated.
All monitors / printers are calibrated differently and colors will appear differently between machines.