Nine ways into the same stones. The 3D Gemstone Simulator shows you a stone. The Brightness & Tilt Analysis measures how it handles light, with the same measured models as the files we sell. The Cut Grading Tool reads a round brilliant’s proportions and grades its cut. The Cut Performance Wheel compares one cut’s brilliance, fire and scintillation with the T73 benchmark or with any cut you choose. The Hearts & Arrows Scope shows a round brilliant’s arrows and hearts as its proportions and symmetry change. The Refractometer, the Dichroscope, the Spectroscope and the Polariscope read the gemstone itself: its refractive index, the two colors a doubly refractive stone splits light into, the dark lines where it absorbs light and whether it is singly or doubly refractive.
-
3D Gemstone Simulator
Build a digital stone and read its 3D gemstone report as you go: 40 cuts in thirty gemstones, the
four Cs, ten kinds of light.
Open the simulator
-
Brightness & Tilt Analysis
See how much light a cut returns face-up, and how that holds as the stone tilts.
Open the analysis
-
Cut Grading Tool
Set a round brilliant’s proportions and read its cut grade, with brilliance, fire and
scintillation across every crown and pavilion angle.
Open the grading tool
-
Cut Performance Wheel
Brilliance, fire, scintillation and five more measures for one cut, against the T73 benchmark or any
cut you choose.
Open the wheel
-
Hearts & Arrows Scope
A round brilliant through a Hearts & Arrows viewer, arrows and hearts side by side, live as you
change its proportions and symmetry.
Open the scope
-
Refractometer
Put a gemstone on the glass and read its refractive index where the shadow edge falls on the scale.
See why diamond reads over the limit.
Open the refractometer
-
Dichroscope
See a gemstone's two colors side by side, computed from measured spectra: tilt the stone, turn the
dichroscope, and see why one color proves nothing.
Open the dichroscope
-
Spectroscope
Read the absorption lines of a gemstone through a prism or a grating, computed from measured spectra.
See why lines name the coloring element, not always the stone.
Open the spectroscope
-
Polariscope
Turn a gemstone between crossed polarizers to tell singly from doubly refractive. Open the conoscope,
read the optic sign, and see why dark is not always singly refractive.
Open the polariscope
Everything in one place
The pieces have always existed, just never together. One site has a beautiful viewer you can’t adjust. Another explains the four Cs clearly but never shows them to you. GemCad, GemRay, GemCut Studio and FreeCAD are superb tools, built for people who already know what they’re doing.
Our simulator brings those worlds into one place. Change the cut, the material, the color or the lighting, and watch the stone respond. There is no wrong setting and nothing to break. If a choice confuses you, choose something else and you’re back on solid ground.
The 3D Gemstone Simulator
Select one of our 40 cuts and one of thirty gemstones. Then set its carat, color and clarity in the report itself. The simulator draws the stone live from the same geometry as our 3D files and cutting files. You can light it with ten kinds of light, from a grading lamp to a camera flash. Turn on the Light map to see where the light that reaches your eye comes from. Turn on the facet mesh to see the true facet edges.
When you like a stone, share it as an image or a link. You can also save its two-page report as a PDF.
Brightness & Tilt Analysis
The simulator shows you a stone. The analysis puts a number on it. It works on 22 cuts, and we checked the geometry of each cut against its GemCad cutting file. The analysis measures how much of the available light a cut returns face-up, for the whole stone and for the table alone. It uses four standard dome models: Light Return, ISO, COS and SC2.
Two settings change the result, and you can move both. Head shadow is the part of the overhead light that your head blocks. Tilt tips the stone under a fixed dome, as it moves on a hand. A chart shows each model from −30° to +30°. Put two cuts side by side, and the analysis measures every figure under the same conditions. Each set-up has its own link, so you can send exactly what you see.
It is a model of the geometry, not an assessment of a real stone. We tell you what it leaves out.
Cut Grading Tool
Move the table, crown and pavilion of a round brilliant and read its cut grade. The tool also shows the one thing that holds the grade back. The chart maps every crown and pavilion combination on our T73 Round Brilliant. Our engine traces the brilliance, and fire and scintillation are models. An outline shows the Excellent proportions for the table you set. Beside the chart, the tool draws the stone four ways, down to a face-up light map.
It grades from proportions, for education: not a grading standard, and not a substitute for a laboratory report.
Cut Performance Wheel
Select a cut and a gemstone to see how the cut performs, eight ways at once. Global performance is on top. Next are brilliance, fire and scintillation, then spread, symmetry, shape-normalized return and how well the cut holds its light when tilted. Brilliance, fire, tilt and the global figure come from our face-up light census. We read scintillation, spread and symmetry from the facets and proportions of the cut. We measure every cut the same way, our house cuts included. Sometimes the census cannot read a cut (a stone with no table, or the heart’s concave notch). Then the wheel tells you so and does not guess.
The wheel compares the stone with the T73 Round Brilliant in the same gemstone, or with any cut and gemstone you choose. It shows where the stone reaches further and where it falls short. One button swaps the two. Beside the wheel is the stone itself, live in 3D or face up as a light map.
Hearts & Arrows Scope
A Hearts & Arrows viewer shows the optical symmetry of a round brilliant: eight arrows face-up and eight hearts face-down. It shows them only when every facet sits where it should. The scope traces both views live from the stone’s geometry, for five brilliants. In DG-Broken Hearts and Arrows in diamond, each heart shows a red crack from its notch most of the way to its point. Change the pavilion, crown and table to see how the proportions shape the pattern. Then twist the crown, tip or turn the pavilion mains, or move the culet off center. You see how quickly a small error breaks the pattern. Each view gives its symmetry as one figure.
Refractometer
A refractometer reads the refractive index of a gemstone, which is how much the stone bends light. It reads it from one polished facet on a glass of higher index. Choose one of our thirty gemstones and a cut. The eyepiece shows the scale dark above the shadow edge and bright below it. A doubly refractive stone shows two edges. Beside the eyepiece, the stone lies table-down on the glass. You see the light that reflects to the scale and the light that goes into the stone. Diamond, moissanite and cubic zirconia are above what a standard refractometer can read. The tool shows what that looks like.
Dichroscope
A dichroscope shows the two rays that a doubly refractive gemstone splits light into, side by side. If the stone absorbs the two rays differently, the two windows show two colors: the stone is dichroic. Choose one of our seven gemstones. Tilt it from across its optic axis to straight down it, and turn the dichroscope. The colors meet at 45° and swap at 90°. We compute the colors from measured polarized absorption spectra with CIE colorimetry. The page shows the numbers behind them.
Spectroscope
A spectroscope spreads white light into its colors. A gemstone in its path takes out the colors it absorbs and leaves dark lines and bands. Choose one of our seven gemstones, and set the path through it and the light. Then look through a prism or a grating. Ruby and emerald show the lines of chromium, sapphire the lines of iron, and the colorless stones show nothing at all. We compute the spectrum from the same measured absorption spectra as the Dichroscope. Point at a line to see its wavelength and its cause.
Polariscope
A polariscope holds a gemstone between two polarizing filters. Crossed, they let no light through, unless the stone changes the light. Choose one of our seven gemstones and turn it. A singly refractive stone stays dark. A doubly refractive stone lights up and goes dark four times a turn. Tilt it to look straight down its optic axis, and it stays dark too: that is the trap. Open the conoscope to see its interference figure. Slide in the red plate to read its optic sign. We compute everything by Jones calculus across the spectrum, from the same refractive indices as the Refractometer.
Studio
The simulator, the analysis, the Hearts & Arrows Scope, the Cut Performance Wheel, the Polariscope, the Dichroscope, the Spectroscope and the Cut Grading Tool can each save what they show as a picture or a video, up to 4K. The formats are square, portrait, full-screen and wide. Your own device traces or draws every frame again at the size you choose, so a video is as sharp as a still.
How they fit together
Start in the simulator to see a stone and what changes it. For the number behind the picture, open the same cut in the Brightness & Tilt Analysis. Read how much light it returns and where it loses light. In the analysis, each cut links back to its page in the cut library and to the simulator. To compare one cut quickly with the T73 benchmark or with another cut, open it in the Cut Performance Wheel.