This envelop already had nice golden design over it and a transparent window.I just pasted a golden paper beneath it , still it looked really simple so added some quilled design to it .
The idea was to copy the printed golden design as it is . Later made the same design but with two colors.
white over golden window and golden over white paper.
Finally the golden paper's edges were dabbed with glue followed by loose gold powder.This gave a nice shimmery look to the envelop.