Render OBJ jewelry models online

What an OBJ file contains

An OBJ file lists the points, faces and normals of a mesh, grouped into named objects or groups. Materials live in a separate .mtl file that sits next to the .obj, and textures are separate image files.

Because each model is uploaded as a single file, the .mtl file and textures are not read, even if they sit in the same folder. That is not a problem for jewelry, because the studio applies its own metal and gem materials anyway. The object names, however, come through with the geometry, and those are what matter.

Named objects become parts

When an OBJ file opens, each named object or group usually becomes its own part in the studio. Parts whose names contain Diamond, Gem, Stone, Ruby, Sapphire, Emerald, Pavé, Halo or similar words start as stones, and the rest start as metal. That makes OBJ a clear step up from STL, which arrives as one part.

To get the most from it:

• Export stones as separate objects, not merged into the metal.
• Give them clear names, such as Center_Diamond, Side_Stones or Halo.
• Keep metal parts separate too if you want two-tone pieces, for example a white gold head on a yellow gold band.

Exporting OBJ from popular tools

Rhino. Select the jewelry, export as OBJ and choose to export objects as OBJ objects or groups so names are kept. Use a smooth mesh setting for round parts.

ZBrush. Export each SubTool you need. Decimate heavy sculpts first, because OBJ files grow quickly with polygon count. See the ZBrush page.

3Design. Use the OBJ export if your version offers it, and keep stones as separate objects.

Blender. Use the Wavefront OBJ exporter, export only the selected jewelry and keep object names. Apply modifiers before exporting.

File size and performance

OBJ is plain text, so it is larger than the same model as GLB, often by several times. Files can be up to 100 MB. If an OBJ export is close to the limit, export GLB instead for a much smaller file with the same names. See the GLB page.

Normals and smoothing

OBJ can store vertex normals, which control how smooth a curved surface looks. Include normals in the export options. Without them, round shanks and bezels can look faceted in close-ups, and any polished surface shows hard edges in its reflections.

Common OBJ issues

1. Stones arrive as metal. The object names did not contain a stone word, or the stones were merged into the metal. Rename or separate them and export again, or select them in the studio and apply a gem.
2. Everything is one part. The exporter merged objects. Turn on export by object or group.
3. Faceted surfaces. Normals were not exported, or the mesh resolution is low.
4. Large file. Switch to GLB for the same model at a fraction of the size.

Workflow from OBJ to finished render

Export the jewelry with named, separate stones and normals included, upload the OBJ to your library and open it in the studio. Check that each stone has a gem material and each metal part has the right alloy, set lighting, background and pose, and export stills or a 360° video. For a full checklist, read preparing jewelry CAD for rendering.