Typically speaking, white light is required for general purpose lighting.
A tiny band of wavelengths are emitted by the GU10, which in turn produces strongly coloured light.
This strong colouration is very characteristic of the energy bandgap of the semiconductor material used in the manufacturing process of the GU10 LED.
Manufacturing an LED to produce white light requires one of two things.
Either by mixing together the red, green and blue light from LEDs, or by implementing a phosphor to change some of the light to other colours.
The former uses many LED chips each of which emit a unique wavelength close together to produce the broad white light spectrum.
There is a significant advantage in this way of doing things and that is that one can alter the varying intensities of each LED to "tune" the character of the emitted light.
However, there is a very high manufacturing cost associated with this method.
In the later method, phosphor converted LEDs (pcLEDs) a solitary short wavelength LED (usually blue or ultraviolet) together with with a phosphor, which absorbs a small amount of the blue light and emits a wider spectrum of white light.
(This method is very alike the method in which a fluorescent lamp creates white light from a UV-illuminated phosphor.
) The significant benefit here is the low manufacturing cost, and high CRI (color rendering index).
However the disadvantage is the inability to dynamically change the character of the light and the fact that phosphor conversion reduces the efficiency of the device.
The low cost and adequate performance makes it the most widely used technology for general lighting today.