"To gild the lily" means to add unnecessary embellishment or ornamentation to something that is already beautiful or perfect, essentially spoiling it by overdoing it. The phrase is a way of saying something is already excellent and doesn't need any further improvements or decorations.
The idiom comes from a line in Shakespeare's King John: "To gild refined gold, to paint the lily". In this context, "gilding" means to add a thin coating of gold, which is a form of decoration. The phrase was later shortened to "gild the lily," and the meaning evolved.
Examples:
- "He tried to 'gild the lily' by adding a fancy new feature to the software, but it only made it more confusing"
- "We should avoid 'gilding the lily' with unnecessary details in our report"
- Google (with editing)
-----------------------------------
For some reason, the idiom reminds me of "The Gilded Age", an American historical drama TV show that is set in the US during the Gilded Age, the boom years of the 1880s in New York City. https://en.wikipedia.org/wiki/The_Gilded_Age_(TV_series)
I was attracted to the show for its history background and its complex yet very interesting storylines. At the same time, I also felt detached: not only it described a very different era, but the fanciness in it was a bit too much for me, or gilding the lily. But that was the point and highlight of show, of course. 
Have a nice Wednesday (with a pic of glided lilies 
)!
