King Roquat is not the first Nome to go by such a moniker. L. Frank Baum's book "Ozma of Oz" tells the story about a previous Nome monarch known as Roquat the Red, who took on the name Ruggedo after having his memory erased.
Roquat has a magical scepter that can turn any living creature into a tiny ornament for his entertainment. Perhaps he learned this trait from his predecessor, Roquat the Red, who was known to be fond of ornaments and other shiny objects. L. Frank Baum's book "The Marvelous Land of Oz" also tells us of an evil witch named Mombi who was fond of turning children or other trespassers into decorative ornaments.
Glinda mentions many of the greatest minds in the history of Oz, including the Wizard, Ozma, and Blinkie of Jinxland. Blinkie was a powerful witch who learned some important lessons about being a good ruler when she was visited by Scarecrow. You can read more about their adventure in L. Frank Baum's book, "The Scarecrow of Oz".