Ray tracing follows straight lines of light through a model of a stone. At each facet it applies refraction and reflection, and it records where the light comes from or where it leaves.
In more detail
Ray tracing describes the geometry of a cut and the optics of its material. Each tracer leaves out some physics for speed, so results from different tracers differ.
How we measure it
Our tools trace light in four ways. The simulator traces per pixel, with up to 64 samples and 14 bounces. The Brightness & Tilt Analysis uses a 132 × 132 grid and 12 bounces. The Cut Grading Tool's brilliance uses an 84 × 84 grid and 12 bounces. The light census uses 3,200 seeded rays and 12 bounces. All four treat total internal reflection as lossless.
Related terms
- Light census: The light census is our ray tracer behind the Cut Performance Wheel, the cut-page scores and the Cut Performance Index. It drops a fixed set of rays on a stone from above and counts where each one leaves.
- Snell's law: Snell's law sets the direction of refracted light: n₁ sin θ₁ = n₂ sin θ₂. The angles are measured from the normal to the surface.
- Fresnel reflection: Fresnel reflection is the share of light that a surface reflects instead of letting through. The Fresnel equations give that share from the two refractive indices, the angle and the polarization.
- Total internal reflection: Total internal reflection happens when light inside a stone meets a facet beyond the critical angle. The facet then acts as a perfect mirror, and all the light reflects back into the stone.
- 3D Gemstone Simulator: The 3D Gemstone Simulator is a free Digital Gemology tool that renders a cut stone as a camera sees it. You choose the cut, gemstone, carat weight, color, clarity, cut grade and lighting.