Nothing to install or update
GemDiagram is a web app: open it on any machine — your studio desktop, a laptop, a Chromebook — and pick up where you left off, always on the latest version.
Gem Cut Studio is a newer desktop faceting tool, and a step up from GemCAD. GemDiagram covers the same design work but runs in the browser on any OS, opens your existing .gcs files, and adds rough-yield planning, a step-by-step cutting assistant, and a client-facing preview link.

Have Gem Cut Studio designs? Import a .gcs file and GemDiagram parses the tier table — angles, distances, indices, and any refractive index — and renders it in 3D. Where the file specifies frosting, that comes across too. No material in the file? GemDiagram snaps to the nearest of 22 built-in materials by RI. Imports open read-only; Save keeps an editable .facet copy.
An honest, side-by-side look. Where a row is marked “coming soon” or carries a plan name, that reflects exactly what GemDiagram ships today.
| Feature | GemDiagram | Gem Cut Studio |
|---|---|---|
| Runs in your browser — nothing to install | ✓ | ✗ |
| Works on Mac, Windows, Linux & Chromebook | ✓ | Desktop (Windows / Mac) |
| Realistic ray-traced render (color, fire, refraction) | ✓ | Limited |
| Live 3D preview while you design | ✓ | ✓ |
| Rough Planner — best-yield orientation search | ✓ | ✗ |
| Cutting Assistant — step-by-step at the machine | ✓ | ✗ |
| Opens your existing Gem Cut Studio files | .gcs | — |
| Frosted-facet preview | Pro | In some .gcs files |
| Screenshot & video export | Studio / Pro | Limited |
| Client Preview link to show buyers their stone | Pro | ✗ |
| No install, automatic updates | ✓ | ✗ |
| Price | Free tier, paid from $20/mo | — |
GemDiagram is a web app: open it on any machine — your studio desktop, a laptop, a Chromebook — and pick up where you left off, always on the latest version.
Beyond designing facets, the Rough Planner finds the best orientation and yield for a piece of rough, and the Cutting Assistant guides the actual cutting sequence (with auto-cut on Pro).
Ray-traced color, fire, and refraction in the Realistic render, plus Ray Studio for tracing light through the stone — judge the look before a single facet is cut.
Pro's Client Preview generates a private link showing a buyer their rough with the finished gem inside it and a short rotating render clip — a closing tool no desktop editor includes.
No tool wins on everything. Here's where Gem Cut Studio is the stronger choice.
As an installed application, Gem Cut Studio runs without a connection and leans on local hardware. If you need a self-contained offline binary, that's a genuine advantage.
If your whole library and habits are already in Gem Cut Studio, staying put has zero switching cost — though GemDiagram imports those files when you want to.
.gcs file and GemDiagram parses its tier table — angles, distances, indices, RI, and frosting where present — then renders it in 3D. Save as .facet to edit.