GemSim

Design your gemstone before you cut it. GemSim is a free 3D gemstone faceting simulator for designing, visualizing, and refining gemstone cuts before touching a real stone. Whether you're learning faceting, exploring fantasy cuts, planning rough stones, or recreating published designs, GemSim brings powerful design tools to iPhone, iPad, and the web. INTERACTIVE 3D SIMULATION • Rotate, zoom, and inspect gemstones from any angle • See design changes instantly in 3D • Preview realistic gemstone renderings • Analyze light return, windowing, and head shadow NEW: FANTASY CUTTING Go beyond traditional faceting with creative cutting tools. • Create fantasy cuts using ball, cylinder, and V-groove cutters • Combine fantasy cuts with traditional facets • Adjust cutter positions and cutting depths • Visualize and experiment with unique patterns in 3D NEW: ROUGH PLANNING & AUTO-FIT Plan your cuts and make better use of valuable rough material. • Import 3D rough stone scans in STL, OBJ, or GLB format • Visualize rough stones and finished designs together • Move, rotate, and scale designs within the rough • Use Auto-Fit to find placements that fit inside the rough • Compare placements to maximize potential yield FACETING DESIGN EDITOR Create and refine designs with precise controls. • Add, edit, reorder, duplicate, and delete tiers • Control facet angles, depths, and indices • Create and reuse custom index sequences • Select meet points directly from the 3D model • Support fractional indices for advanced designs • Toggle tier visibility and undo changes FROST EDGE Create decorative frosted edges directly in 3D. • Select individual or symmetrical groups of edges • Adjust frost width for precise effects • Frost crown, pavilion, and girdle edges • Generate editable frost tiers automatically • Preview frosted facets in realistic rendering • Include frost details in printable diagrams DESIGN LIBRARY Explore thousands of classic and public gemstone designs. Search by shape, name, designer, or dimensions. Preview, load, and customize designs instantly. CLOUD STORAGE & SHARING Create a free account to save and share designs across devices. • Store up to 100 designs in the cloud • Share through public links or with specific users • Control View Only or View + Copy permissions • Manage access separately for each design An account is optional. Core features work without signing in, and local file storage remains available. IMPORT, EXPORT & PRINT • Save and open editable GemSim project files • Export gemstone designs as 3D models • Generate printable cutting diagrams and instructions • Work with local files without an account BUILT FOR GEM CUTTERS Whether you're a beginner, experienced faceter, hobbyist, student, or gemstone designer, GemSim lets you experiment with angles, proportions, fantasy cuts, frost patterns, and complete designs before cutting real stones. Make mistakes on the screen instead of on the dop. GemSim is free to use, with no subscription required to design, edit, or simulate gemstones. Start designing today and discover what's possible before you make the first cut.