chrysography

from The Century Dictionary.

• noun The art of writing in letters of gold, practised by the writers of manuscripts in the early middle ages.
• noun The writing itself thus executed.
• noun In Greek antiquity, the art of embroidering in gold, of inlaying other metals with gold, and the like.

from the GNU version of the Collaborative International Dictionary of English.

• noun The art of writing in letters of gold.
• noun A writing executed in letters of gold.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The use of gold lettering in manuscripts