Light Performance Education
SO BRILLIANT! UNDERSTANDING YOUR DIAMOND’S LIGHT RETURN
Have you ever gazed at a diamond and been captivated by its brightness and sparkle? And fascinated by the way it catches a beam of sunlight and turns it into an enchanting pattern of reflections and fiery light on the surfaces around it? This is the beauty of a diamond's LIGHT RETURN. Diamonds with a low percentage of light return look dull and dark.
How do you know if you are getting a diamond with great light return?
The amount of light a diamond returns to the viewer’s eye is known as Light Return and this is measured in three categories: Optical Brilliance, Fire and Scintillation. Each of these aspects is measured and evaluated on a scale of Poor, Fair, Good, Very Good, and Excellent. Diamonds graded Excellent in all three categories have the highest levels of light return.
What makes a diamond shine brightly and sparkle in sunlight and candlelight?
It's a combination of the outstanding physical properties unique to diamond - it’s the hardest known gemstone, which gives it outstanding luster and ability to shine--and precise faceting which makes some diamonds brighter and more brilliant than others. Master craftsmen reveal the hidden beauty of diamonds in the rough. How much a diamond reflects, refracts, and releases its inner beauty is determined by how well it is cut and polished.
DIRECT ASSESSMENT
The most true-to-life way of determining the quality of a diamond’s light return is through direct assessment. GCAL examines how a diamond appears to the eye and the way each diamond actually performs in the real world, rather than relying solely on a theoretical model and mathematical analysis.
This means that if your diamond comes with a GCAL light performance certificate, it was evaluated independently in our lab by our expert technicians who captured a series of measurements and analyzed the quantity of light return. These measurements are recorded as the images included on the GCAL certificate and the videos on the digital verification webpage that are all unique and specific to only one diamond: every image on a GCAL certificate is an actual image of that diamond; no generic "sample" photos are ever used.
Another benefit of direct assessments is that every shape diamond can be evaluated.
OPTICAL BRILLIANCE ANALYSIS
Brilliance is the overall return of white light to the viewer. It is measured by GCAL's proprietary technology to the thousandth decimal place and is represented in the Optical Brilliance image seen on the certificate. In the image, the white represents the light return, and the blue represents areas of light loss or light leakage.
The quantified light return is graded on a scale of: Excellent, Very Good, Good, Fair and Poor.
1.
Areas of Light Leakage are highlighted and measured versus the overall light return to a thousandth of a decimal place.
2.
The Optical Brilliance image shows the leakage as dark blue and the light return as white. The gray areas are weaker light return.
An example of a poorly cut diamond that lacks Brilliance
An example of a diamond with Excellent Brilliance and Symmetry
FIRE ANALYSIS
Fire is the captivating, colorful sparkle that diamonds are known for. Fire is the result of white light traveling through a diamond and being dispersed into its rainbow of spectral colors. These flashes of color contribute to sparkle and are best viewed as the diamond moves. The fire video is shown on the digital certificate verification page. Each fire video is composed of 200 frames that are processed to analyze the quantity and size of colored light return as the diamond is tipped and tilted.
Excellent Fire Compared to Good Fire in Round Brilliant Cut diamonds
Excellent Fire Compared to Good Fire in Oval Brilliant Cut diamonds
Excellent Fire Compared to Good Fire in Princess Cut diamonds
SCINTILLATION ANALYSIS
Scintillation is the flashes of light, or sparkle, produced when light is reflected from a diamond as it moves. GCAL measures scintillation using Gemprint technology which shines a single beam of light into the center of a diamond and captures the light return pattern as the diamond is rotated. The total number of points of light reflected back out of the diamond are then calculated and compared on a scale against other diamonds of the same shape and faceting style. The more points of light refracted and reflected back out of the diamond, the greater the scintillation.
This animation shows the light returned from a single beam of light when your diamond is rotated in nine positions, and the total culmination of points. The scintillation images are all captured and evaluated in full on a square background and then cropped to the shape outline on the certificate and in the thumbnails.
Scintillation Patterns of Round Brilliant Cut Diamonds
