UV mapping
Assigning 2D texture coordinates to a 3D mesh so images such as textures can be placed on its surface.
Does jewelry need UVs
Often, no. Polished gold, platinum and silver are uniform materials described by colour, metalness and roughness, so they render correctly without textures. Faceted gems need no textures either, because their look comes from refraction.
UVs matter when a surface carries an image based detail, such as:
- a brushed or satin finish with a direction,
- hammered, sandblasted or florentine textures,
- engraving or patterns created with a texture instead of geometry,
- enamel artwork or printed designs.
Formats and UVs
GLB, glTF, OBJ and FBX can store UV coordinates. STL cannot, so an STL file always arrives without UVs. Rhino 3DM files can carry texture mapping set in Rhino, but results depend on how the file is exported and read.
Practical advice
If a texture looks stretched or shows a seam in a render, the UVs are the cause. Fix them in your 3D tool before exporting. For engraving that must look sharp in close-ups, model it as geometry instead of relying on a texture, because a texture loses detail when the camera gets close.
When textures are not needed, skip UV work entirely and let PBR materials do the job.