Can dollar store decorative colored glass be used in a gas fire pit?

First of all, are you sure it's glass? It could be cheap plastic and you sure would not want to try and put that anywhere near a hot fire. Second, even if those "jewels" are glass, I wouldn't use them because they might explode or melt if they get hot enough. You need a special kind of glass (fire glass) to stand up to the heat of a fire, that's why it's expensive.

I read somewhere that a broken tempered glass window works. When tempered glass is broken it breaks up into tiny pieces and holds up to the heat very well. You could probably get a second hand window cheap at a Re-store or scrap hardware place.

Info@easyfirepits.com says that YES you can use Dollar Store glass beads. This company sells DIY fire pit kits.