Light emitting sign and display surface therefor

A light source comprising:

• at least one blue emitting LED operable to generate blue excitation light and
• a light emitting surface comprising a light transmissive substrate and at least one phosphor;
• wherein the at least one LED is configured to irradiate the light emitting surface with excitation light such that the phosphor emits light of a second wavelength, wherein the light emitted by the source comprises a combination of blue light from the LED and the second wavelength light from the phosphor;
• wherein the light emitting surface is interchangeable thereby enabling the source to generate different selected colors of emitted light using the same at least one LED;
• and
• wherein the source is configured to generate white light of a selected color and further comprising a reflective color enhancement layer positioned parallel and adjacent to the at least one phosphor, wherein the reflective color enhancement layer comprises a blue material configured such that white light reflected from the light emitting surface appears substantially as white light of the selected color.