Understanding Light Leakage in Gemstones: A Guide to Brilliance and Cutting Precision
- Samuel Cini
- Jun 19
- 3 min read
Updated: Jun 26
In the world of gemstones, beauty isn’t just about colour or clarity it’s also about how light interacts with the stone. One of the most important yet often overlooked aspects of a gemstone’s appearance is light leakage. Whether you're a jewelry enthusiast, collector, or someone looking to reset or recut a gemstone, understanding light leakage is essential to appreciating and enhancing the true brilliance of a gem.
What Is Light Leakage?
Light leakage in gemstones refers to the loss of light that enters a gem but escapes through the bottom or sides, rather than being reflected back toward the viewer's eye. This phenomenon reduces a gemstone’s brilliance, fire, and scintillation the sparkle and flashes of colour we associate with well cut stones.
In summary: if a gemstone leaks light, it will look dull or washed out, even if it’s made from high-quality material.
How Light Behaves in a Gemstone
When light enters a well-cut gemstone, it should ideally reflect off internal facets and return through the top (called the table). This process is what creates the gem’s brilliance and fire. But when the stone is cut at the wrong angles or has poorly aligned facets, much of that light "leaks" out the bottom or sides, making the gem appear lifeless.
This problem is particularly common in:
Shallow cuts (light passes straight through)
Overly deep cuts (light bounces incorrectly and escapes)
Asymmetrical or poorly polished facets
Misaligned crown and pavilion angles
Visual Signs of Light Leakage
You don’t need to be a gemologist to spot light leakage. Here are some signs to watch for:
A "window" in the centre of the stone where you can see straight through it
A lack of sparkle or dull appearance, even under bright light
Poor contrast between light and dark areas within the stone
Flat, glassy look without internal reflections
These are especially noticeable in faceted gemstones like sapphires, rubies, emeralds, tourmalines, and even diamonds.
Why Cutting Matters: The Role of a Gem Cutter
The cut of a gemstone is one of the few aspects humans can control. While color and clarity depend on nature, cutting determines how well a gemstone interacts with light.
A skilled gem cutter (also known as a lapidary artist) understands how to:
Calculate ideal proportions based on the gem’s refractive index
Align facets to direct light properly
Preserve weight without sacrificing brilliance
Customise cuts to match a gem’s shape and intended setting
This is where professional gemstone cutting services become invaluable — especially for stones with visible light leakage.
Correcting Light Leakage Through Recutting
At Rosetti Gems Antwerp, we offer precision gemstone cutting and recutting services that are specifically designed to fix light leakage and enhance brilliance.
Here’s how we help:
Recutting shallow or deep stones to optimal proportions
Refaceting to improve symmetry and light performance
Custom cuts designed for maximum brilliance based on each stone’s properties
Window removal to eliminate the see-through effect common in poorly cut gems
Our team uses advanced lapidary equipment and techniques to ensure that every gemstone is cut to exacting standards.
The Value of Light Performance in Gemstones
Light leakage is more than just a technical issue it’s one of the key reasons a gemstone might not look as beautiful as it could. A gem’s ability to sparkle depends on its interaction with light, which in turn depends on how it’s cut.
Whether you’re restoring an heirloom gem, upgrading a centre stone, or designing custom jewelry, our expert gemstone cutting services can help correct light leakage and unlock your gem’s full potential.
Ready to Maximise Your Gemstone’s Brilliance?
If your gemstone looks dull, lifeless, or windowed, we invite you to reach out to our team of master cutters. We’ll evaluate your stone and recommend the best approach whether that’s a simple refacet or a complete recut.
📩 Contact Rosetti Gems Antwerp today to learn more about our custom gemstone cutting services and how we can eliminate light leakage for a more brilliant, sparkling gem.
