Why you cannot see through glass to another transparent object on Roblox

Roblox's Glass material does not draw anything non-opaque behind it. Not another glass part, not particles, not beams, not water, not decals. That is a deliberate performance limit on the platform and it has been that way for years.

So the export chooses per object. A single glass part keeps real refractive Glass, because there is nothing transparent behind it to lose. A set of many glass parts, such as fractured shards or a pool of particles, drops to smooth plastic instead, which sorts and layers correctly.

Two of your material settings drive the look. Transmission becomes transparency, capped so the surface still reads as a surface. Roughness becomes reflectance, which is the sheen that separates a gem from tinted plastic.

Godot ignores glTF transmission entirely, so the Godot Kit rebuilds the look at runtime: transmission becomes alpha under the same ceiling, and roughness carries across directly.

The practical rule: do not build an effect that depends on seeing particles through a glass part on Roblox.