This necklace is a tribute to House Tyrell of Highgarden from the series A Song of Ice and Fire, also known as Game of Thrones. I can just see Margaery wearing something like this, decked out in the green and gold colors of her house and proudly displaying the gold rose of Highgarden.
That's gorgeous, I'd want it regardless of the reference! hardly ever wear jewelry though.. dunno if it's worth getting something just to sit in my drawer forever