I have recreated medieval manuscripts based on sources from different locations and timeframes. Most of these have become award certificates for members of the Society for Creative Anachronism.
Most are done using gouache paint, an opaque watercolor. The gold may be gouache, shell gold or leaf gold.
Here are some of the more interesting ones that I have done. Click on the small images to get more detail. Click on the larger image to see that image even larger.
Here is more information about the selected manuscript.