dekker3d/blender-gem-designer

Blender Gem Designer is an add-on for the 3D software Blender that lets you design faceted gemstones, the kind of cut you see in jewelry, and preview how light would realistically behave inside the finished stone. You build a gem as a stack of tiers, each defined by angle and rotational or mirror symmetry, and see the shape update live using Blender's Geometry Nodes system. The author built it because other gem faceting design tools give previews that do not look much like how a real stone would appear once rendered. The README is upfront that most of the code was written with AI assistance, with the author guiding and steering the process, and notes this may explain any unusual code structure or heavy commenting, while stating the add-on still works and has been tested. You can import existing designs from other faceting tools, specifically Gem Cut Studio and GemCAD file formats, and the add-on will figure out the tier layout and apply the correct gem material automatically if the file names one. The included materials go beyond simple colored glass: they simulate light absorption that deepens color over longer light paths, dispersion that splits red and blue light like a real diamond, birefringence for stones that need it, and even a subtle fingerprint smudge texture so a gem does not look unnaturally perfect. A Scene Setup panel automates the tedious parts of rendering, including noise settings, light bounce counts, camera placement with depth of field, and a background setup that keeps reflections realistic while keeping the visible background clean. To install it, you download a zip file from the project's releases page and add it through Blender's add-on preferences, after which a Gem panel appears in the 3D viewport sidebar. From there you can start a new gem from scratch or import an existing design file, then apply one of over a dozen built in gemstone material presets like ruby, sapphire, or diamond. It requires Blender version 5.1 or later and the Cycles renderer, since the materials depend on Cycles specific shader features. The project is licensed under GPLv3.