Artemis- Swapping Blue Diamond

He paused in disbelief, his eyes widening. 'Tell me this is not she,' he said, picking the tiara off the ground where Holly had dropped it. 'She lies in the dirt like some cluster of common stones. This truly is a circus.'
...

Artemis closed his fist around the blue diamond on the tiara's crown. It was already loose in its setting. All he had to do now was leave. Simple. Let the LEP clean up their own mess. But even before he heard Holly's voice, Artemis knew that it couldn't be that easy. Nothing ever was.

'Don't move, Artemis,' said the fairy captain. 'I won't hesitate to shoot you. In fact, I'm quite looking forward to it.'
...

Holly scowled behind her mask. There must be something she could salvage from this. 'Give me that tiara. And the helmet.' Artemis rolled the helmet across the ground.

'The helmet, certainly. But the tiara is mine.'

'Give it to me,' shouted Holly, authority in every syllable. 'Give it to me, or I will stun you both and you can take your chances with Ehrich Stern.'

Artemis almost smiled. 'Congratulations, Holly. A masterstroke.' He took the tiara from his pocket, tossing it to the LEP
officer. 'Now you can report that you broke up a gang of dwarf jewel thieves, and recovered the stolen tiara. A clutch of feathers in your cap, I would think.'
...

Artemis watched his nemesis lift slowly into the night sky. And just as the crowd appeared around the corner, she vibrated out of the visible spectrum. Only a fairy shaped patch of stars remained.

Holly really makes things interesting, he thought, closing his fist around the stone in his pocket. I wonder if she will notice the switch. Will she look closely at the blue diamond and see that it seems a little bit oily?

-The Seventh Dwarf, Chapter 5