If we ignore the White Crystal for a bit, we're left with Red and Blue. Castlevania lore just so happens to have two closely connected items of those exact colors. And they show up just fifty years later.
https://castlevania.fandom.com/wiki/Bracelets_of_BrotherhoodAnd guess who gave those bracelets to Juste and Maxim?
https://castlevania.fandom.com/wiki/Lydie_ErlangerMy addendum to Reinhart77's theory: Simon and his two vampire hunting buddies held onto their respective crystals. All three had grandkids: Juste, Maxim, and Lydie, who would grow up together as childhood friends. Years later, Lydie turned Simon's and Grandpa Kischine's Red and Blue Crystals into mementos of their friendship. The Red became part of JB's Bracelet and the Blue became part of MK's Bracelet. Both allowed Juste to save Maxim and Lydie during HOD.
This brings up an interesting idea. Maxim went on a "training expedition" when he was really hunting for Dracula's relics. He just might have used the Blue Crystal power in his bracelet to drain a lake in search of those relics, like Simon did before him.
As for the White Crystal, who knows? Maybe Lydie made an EL Bracelet for herself. Or maybe it became part of something else entirely. Something that would help another hero save the day by letting him see through evil illusions.
https://castlevania.fandom.com/wiki/Holy_Glasses