i agree with Genepi and Aurorous in the fact that the jewel horns do kind of resemble a few of the other breeds, i think varying them up a little bit will certainly help their popularity!
its nothing special, but this is the first thing that came to mind for them
a lot of the crystal breeds seem like they're meant to be more delicate, so with a longer and narrower snout, i feel like the Jewel horns will fit into that category while still looking different from existing breeds. The spot markings are a mix of both the older styled snout strip that they used to have and the current solid stripe.
i imagine they meet in the middle like this to form a marking that doesnt quite reach all the way down the muzzle, but is significantly longer than the other markings.
As for horns, i'm especially fond of the shorter ones that the Jewel Horns had for a little bit, My girl
Avalon has the SHINIEST horns and i love them to bits! i'd love to see those make a comeback!
Alphas and Omegas could have additional or fewer crystals and fancier or less stunning spotted markings, respectively~