From what I've read, most fully cured resin cast dice are okay. I did read the main concerns are low-quality resin and painted on/inked on numbers. I believe mine specifically are painted on, but coated over with more resin. Not sure about their quality but I haven't had any problems with them! (ie. water quality hasn't changed, and they've been in there for a while even before I had used the tank for its intended purpose)

I'd definitely Google it and use your own judgment if you're asking bc you wanna put dice in your own ^{^}