"...Have you not had a Sinestro yet? What is this timeline... Or it could have been out in space in a way that didn't really come to your attention, I guess.
"Yes. Green Lanterns draw their power from the Green Light of Will; there are at least six other colors, and possibly more than that but those ones were strange. 'Gold' is not a frequency, for crying out loud. But anyway. In ascending order, you have the Red Light of Rage, the Orange Light of Avarice, the Yellow Light of Fear - which, in a roundabout way, is why Green Lantern power rings don't work on Yellow - the Green Light of Will, the Blue Light of Hope, the Indigo Light of Compassion, and the Violet Light of Love - also a Light Earth should have encountered at some point; that's the Star Sapphires.
"There's also White, and Black, as I mentioned earlier, but those are... special cases.
"Each of them does something unique, if I recall correctly, though some of them might be specific to their Corps rather than the Light itself; certainly I don't expect the Reds' whole... incredibly-destructive Rage-plasma blood... Thing... to be necessarily built in to the Light when I'm fairly sure it was built in to their Rings by the Corps', eh, 'commander' for some value of, who... He had quite a grudge against Oa when he started doing things, and I don't think he was wrong to have it, considering that, if my information is right, he did it after one of Oa's projects massacred most of an entire Sector - but, well, he decided to combat an atrocity by perpetrating another. So, anyway. Red Lanterns have... That. The singular Orange Lantern that presently exists has demonstrated the ability to assimilate... Well, almost anything. Yellow is empowered by ambient fear, while Blue rings are recharged by ambient hope; Blue Light is capable of healing. Up to and including a literal star, if certain sources are correct. Green has a special interaction with Blue, getting effectively supercharged by it. Indigo can replicate the effects of the other Lights in the presence of the right stimulus. Violet... The Star Sapphire Corps has this weird... 'Trap people in a rock and possibly convert them to Violet' thing but I think that that is maybe more likely to be because of the rock, moreso than necessarily the Light. It's just bizarre that the Violet Light turns you into a yandere, otherwise. Love is not inherently possessive and if the universe thinks otherwise it can fight me." She gestures, sharply. "But I digress. What I was thinking about, is making foci much more limited-purpose than a Ring, that take advantage of the properties of one or more frequencies of the Emotional Spectrum to perform specific tasks. And note, specifically, 'frequencies of the Emotional Spectrum', because I am aware of at least one 'Lantern' who perceives the Lights as sounds, which may or may not have any strategic import but gave me some ideas."