Book/Source: Silmarillion, The Hobbit, LotR
Disclaimer: Tolkien's the genius, not me.
With a sharp hiss and a loud boom, the fireworks shot into the night sky and exploded, sending showers of colorful sparks raining down on the delighted audience. Gandalf laughed and set his staff to another fuse, the hidden ring on his finger humming with power.
For kindling hearts to hope and valor and action, Narya had been entrusted to him. Entertaining hobbits was probably not what Círdan had had in mind at the time, but as Gandalf watched the Old Took laugh while holding his little bright-eyed grandson Bilbo, he could not think of a better use for it.