Small backstory detail time. So Takame has a little sister back home who he loves very much. She's also a crafter cause in FFXIV you can craft gear. It's terrible, never do it.

But anyway, he carries a ring around that she made him. Technically it's the Star Spinel Ring of Slaying but in this case shush it's something she made and his Purple Dusk Jewel is now embedded in it. It looks like this.

Pretend the stone is lighter... The ring is actually too small for him (contrary to the screenshot) so he wears it around his neck as a charm on a necklace like this.