Installation

In Blender open Edit, Preferences, Get Extensions, then use Install from Disk and pick the jewelry_generator zip.

Usage

1. Open the Jewelry tab in the 3D viewport sidebar (N). With nothing selected, pick a category and a design picture, then press Add. You can also use Shift+A, Mesh, Jewelry.
2. The top of the panel shows the piece, its size and carat total, quick metal swatches, the gem and cut, the carat and (for rings) the ring size. Surprise makes a random new piece.
3. The tabs hold every setting: Design (the piece's own shape), Stone (cut, gem, size and proportions), Setting (prongs, baskets, bezels, halos), Accents (pavé and side stones), Finish (metal, finish, wear, pearls, enamel) and Studio.
4. Studio adds a one-click photo set with lights, backdrop and camera, in EEVEE or Cycles.
5. Convert to Mesh turns the piece into plain meshes for export; Delete removes it with all its parts.

Use Rendered view to see the gems sparkle. Rainbow fire shows in both engines; Cycles gives the most accurate refraction.