Cert Ray Tracer
v0.54Grading a stone of your own? Request the full light-performance report: light return map, flash map and our write-up, sent by email.
3D ray-traced simulation from certificate proportions. Not a photo of this stone. Accurate representation of optical performance, but it does not account for facet variations and does not show clarity or inclusions. See more.
As seen through a hearts-and-arrows viewer. The pattern only lines up when the stone is looked at square on, so this view does not turn. The simulated stone is cut perfectly evenly, so the pattern shows how its proportions shape the hearts and arrows, not how evenly the real stone is cut.
Red is light from the best angles and gives the strongest return. Green is softer light from low angles. Blue is where the viewer's own head blocks the light, which gives the stone its contrast. Black (white when backlit) is light escaping through the bottom of the stone.
Flash map
A flash map adds up the light the stone returns through one full precession, the angles a ring is most often seen from. Brighter and more colourful flashes mean a livelier stone.
What to look out for
Tools
For every stone: light-return shares face-up and tilted 15° (red, green, blue, leakage); a precession under Studio light and under Worn light (mean light returned, share of dark samples, flicker = mean change of each spot between poses); and the spot-light flash figures. Numbers from the simulation only, for comparing stones with each other.
Your stones
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Edit values
From the certificate
Star and lower half
Built geometry
Questions and method
Is this a photograph of the stone?
No. Every picture here is a 3D ray-traced simulation from the proportions printed on the stone's certificate: table, depth, crown angle and pavilion angle. It is an accurate representation of the optical performance those proportions give, but the certificate does not record inclusions, growth tint or striation, haze, or small differences between one facet and the next, so none of those are shown. The body colour is an approximation from the colour grade letter.
What do the grade score, Pass, Fail and Exceptional mean?
The score says how closely the stone's proportions sit to the combination we look for. Pass means the stone cleared our proportion screen; Fail means it did not. A stone can score well and still fail on a single limit. Exceptional is a Pass with a score of 95 or more: the crown and pavilion sit almost exactly on the complementary line, which is rarer than a lower pass. It is still a judgement of proportions, not a guarantee about the stone. Carat, colour, clarity and cut are copied from the certificate.
How far can a score from certificate numbers be trusted?
What are Light box, Studio light, Spot light and Worn?
Light box shows the stone the way a product photograph would. Studio light is even light from all round with the camera overhead; it shows the pattern of light and dark. Spot light is a dark room with small lamps; it shows the flashes and their colours. Worn shows the stone as it sits in a ring in ordinary room light: light from the room above and a window to one side, your own head close overhead, and the finger and setting dark behind the stone.
What do the colours in the Light return map mean?
The map colours the stone by where its light comes from. Red is light from 45 to 75 degrees above the girdle, the angles that return the most light. Green is light from below 45 degrees, which is softer. Blue is light from above 75 degrees, where the viewer's own head is in the way; this is what gives a stone contrast. Light from below the girdle is leakage: black on the dark tray, white when backlit.
What does the Hearts and arrows view show?
It shows the stone as it looks in a hearts-and-arrows viewer: a dark tube with a bright translucent band close round the eyepiece, looked through square on. Table up, a well-proportioned round shows eight bright arrows; table down, eight bright hearts. The view does not turn, because the pattern only lines up square on: a tilt of three degrees already pulls the arrows out of line, and by ten degrees they are gone. In a real stone the pattern is a test of how evenly the facets are cut. Every simulated stone is cut perfectly evenly, so here the pattern shows only how the stone's proportions shape the hearts and arrows; it cannot show whether the real stone has them.
What is Precess, and how do I turn the stone?
Precess rocks the stone in a small circle about its point, the way a ring moves on a hand. Drag the stone to turn it in any direction; let go mid-drag and it keeps turning. The view buttons jump to standard angles. The first time a view is shown it is ray traced, which takes a moment; after that it plays back for the rest of your visit.
What is a Flash map?
It is one full precession under spot light, added up into a single picture. Areas that catch the lamps more often or more strongly are brighter, and areas whose flashes are split into colour keep that colour. It is made from the simulated stone and this page's own lamps, so use it to compare one stone here with another, not as a measurement of the real stone.
Where is the light return map?
On this page every picture is computed in your own browser, and the light return map is not among them. Each stone we sell carries one on its own page, made ahead of time. For a stone of your own, request the full light-performance report below the viewer and we will send it.
How do I turn the stone?
Drag the stone to turn it in any direction; it stops where you let go. The Angle buttons jump to the standard views: face-up, tilted, side and pavilion. Each view is ray traced when it is shown, which takes a moment, and the tracer stops once the picture is complete. Every picture here is still; the moving views are on each stone's own page, made with the same tracer ahead of time.
How do I compare two stones?
Press Compare two and load a stone into each side. True relative size draws the smaller stone smaller by the ratio of their diameters. Press Face-up and look at both square on, then tilt them a little by dragging. Look at the arrows in Studio light, the colour of the flashes in Spot light, and the Light return map.
What happens to a certificate I drop in?
It is read inside your browser and nothing is uploaded. We do not look the report up with the laboratory. A picture of a certificate is read by text recognition, which can misread a figure, so check the numbers under Edit values against the certificate.