A Genuine Microsoft Label (GML) should be found on new devices that have been preinstalled with Pro editions of Windows 8 and on all devices preinstalled with Windows 8 shipping into China (except for those device types noted below). The label is used to help users identify the edition of Windows 8 preinstalled on a device and is also an indicator of whether the device is preinstalled with genuine Windows. Most commonly the label is found on the back or bottom of the Windows 8 device.
Some devices, such as Windows Phones or Windows tablets, may not have a GML affixed to the device. There are multiple things to look for when buying a Windows device to help identify if it is genuine. Get tips about buying genuine Microsoft software or make sure you have the right licensing for your business.
See the following examples of the Genuine Microsoft Labels:
The color shift on the label is designed to change from one color to another when viewed from different angles, making it easy to determine if it is genuine.
Windows 8: magenta to green
Windows 8 Pro: blue to purple
Windows RT: turquoise to purple