A Moment

The only reason he had come here in the first place was because he felt that Amethyst might be in trouble. The moment he saw Crystella's fan, he recognized that its build was nearly identical to Madeleine's. Fans were an incredibly niche and rare weapon to begin with, there was no universal build standard for them like there might be for other weapons. So, seeing two nearly identical products flipped Dyon's antennas up. 

As for why he thought Amethyst might be in trouble, it was simple really. What was she doing with the Dark Flame world? Why hadn't she gone to the Phoenix Hegemon? 

Granted, her relationship with the Fire and Ice Phoenix Clans wasn't exactly the greatest due to what they had done to her parents, but those were matters of the mortal plane.