Everything on this page is a limit or a definition. The stone pages carry one notice with the pictures: 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. The rest is here.
Is this a photograph of the stone?
No. Every picture here is simulated from the proportions printed on the stone's certificate: table, depth, crown angle and pavilion angle. 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 and Pass or Fail 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. Carat, colour, clarity and cut are copied from the certificate.
How far can a score from certificate numbers be trusted?
Standing caveat: derived from averaged certificate proportions, which hide azimuthal variance, painting and digging, and optical symmetry. Contrast — the dark/bright patterning that makes a stone sparkle rather than merely glow — cannot be accurately predicted from these numbers. This tool screens and sorts on geometry; it eliminates non-performers, but it cannot rank the survivors. Final grading belongs on the actual stone, with a tool such as an ASET scope.
ASET® is a trademark of the American Gem Society, named here as a third-party instrument. We are not affiliated with it; see Legal notices.
Where is the laboratory report?
Each stone page shows its IGI report number under Details, with a link that opens the report check on IGI's own website. We do not host or copy the report, and this site never contacts the laboratory itself; the link is yours to follow.
What are Studio light, Spot light and Worn?
Studio light is even light from all round with the camera overhead; it shows the pattern of light and dark, the way a product photograph would. 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 do the Arrows and Hearts views show?
They show 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 views do 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. On the stone pages the precession is a short video rendered in advance, so nothing is traced on your phone. In the viewer, 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.
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, then Precess: most differences only show in motion. Look at the arrows, the colour of the flashes, 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.
Which stones do you list?
Round brilliants only, with an IGI report, colour D to G, clarity IF to VS2, from one carat upward, and only those that pass our proportion screen. Other shapes need facet data that a certificate does not print, so we do not grade or sell them.