Lesson 19 · Diamonds & Engagement Rings · 31 seconds
Round is the shape. Cut changes the light.
Round describes a diamond's shape; cut quality covers proportions and craftsmanship that influence how light travels through the stone. Change the facet angles and you change where the light goes, and polish and symmetry matter too.
What this lesson shows
Facet angles steer the light.
A simplified two-dimensional light-path diagram traces light into a round brilliant section using refraction and total internal reflection. Only the pavilion angle changes, and the light leaves in different directions. It is not a cut grade.
Three quick takeaways
What to actually do when you shop
- Round is the shape. Cut quality covers the proportions and craftsmanship that influence how light travels.
- Change the facet angles and you can change where the light goes. Polish and symmetry matter too.
- Look beyond the shape name: check the cut information and see the stone in motion.
The diamond footage is AI-generated illustration. The light paths are a simplified 2D calculation with a single wavelength of light, not a 3D light-return simulation or a grade. The narration uses an AI-generated voice. Captions are shown in the video.
Read the transcript
Round is the shape. It does not tell you the whole sparkle story. Cut quality includes proportions and craftsmanship that influence how light travels through a diamond. Change the facet angles, and you can change where that light goes. Polish and symmetry matter too. So look beyond the shape name in the listing. Check the cut information and see the stone in motion. Explore more in the Aydins Jewelry Learning Center.
Sources
- GIA, six things to know about the diamond cut grade: 4cs.gia.edu/en-us/blog/gia-diamond-cut-grade-six-things-to-know/
- GIA, diamond quality factors: www.gia.edu/diamond-quality-factor
- GIA, diamond cut: 4cs.gia.edu/en-us/diamond-cut/
Related lessons
Diamond cut guide · the Aydins primer on cut.
Same diamond, three lights · how lighting changes the look.
VS versus VVS · what a clarity grade can and cannot tell you.
Next step
Compare round diamonds in motion.
Check the cut details for each stone you are considering.