Everything you need to know about blue nuance and phosphorescence before purchasing a lab grown diamond.
Diamond Education
What is blue nuance?
Blue nuance refers to a subtle blue color tinge that can appear in HPHT diamonds due to the presence of boron introduced during the growth process. Lab diamonds with measurable boron are classified as Type IIb rather than Type IIa.
An HPHT grown emerald cut with blue nuance. This diamond received an H color grading from IGI.
A CVD grown emerald cut without blue nuance. This diamond received an H color grading from IGI.
How does blue nuance occur?
Boron is sometimes introduced during HPHT diamond growth to help offset nitrogen. Once present, it is difficult and costly to remove. Excess boron can indicate a diamond grower is more concerned with speed of growth than with quality.
Do all HPHT diamonds have blue nuance?
No. Many HPHT grown lab diamonds are beautiful, icy white with no blue undertones present. Blue nuance is not listed on a grading report and is typically only identifiable by an in-person inspection. When diamond growth is slower and more carefully controlled, the likelihood of excess boron is reduced. Lab grown diamonds without blue nuance are more difficult and expensive to grow and command higher prices.
How does it present to the naked eye?
Lab diamonds with blue nuance will display an unnatural blueish undertone. Identifying the color can be challenging without experience, but once seen, it is easy to spot. Blue nuance is extremely difficult to spot in v360 videos on e-commerce websites because the color and lighting of the videos can be manipulated to mask blue undertones.
Lab diamonds and mined diamonds are both graded for color culet up. The lab diamond on the left is HPHT grown with blue nuance, the diamond on the right is CVD grown with no boron present.
How does this affect grading?
Lab diamonds, just like mined diamonds, are graded for color face-down, or culet up. Their color is assessed relative to other diamonds and assigned a grade from D to Z.
An HPHT diamond with noticeable blue undertones present will receive a lower color grade than one without them. This is one of many reasons in-person evaluation by a lab diamond expert matters. A diamond can appear different in real life than it does on a grading report, or in a video, and expert review ensures what you choose looks exactly the way it should.
Lab diamond grading reports may also say “blue nuance” in the comments.
What are alternatives to blue nuance?
Some growers introduce titanium or aluminum to offset nitrogen during diamond growth. Excess titanium can leave an HPHT diamond with a gray undertone rather than blue. These gray undertones are difficult to spot in 360 videos online and are not obvious or noted on a grading report.
How does this affect the diamond other than color?
The presence of boron can make a lab diamond electrically conductive. As a result, some lower-quality diamond testers may incorrectly identify a lab diamond as moissanite.
Boron can also cause phosphorescence, where the diamond emits a visible orange glow after exposure to UV light.
Shining a UV light on an HPHT lab diamond in darkness can expose phosphorescence.
An HPHT diamond with strong phosphorescence will glow orange once you turn the UV light off.
What is phosphorescence?
Phosphorescence occurs in type IIb lab diamonds as a light blue or orange glow after exposure to UV light. The glow can last a few seconds to several minutes.
Phosphorescence is related to fluorescence, but not the same. Fluorescence is a quality that is visible only during UV exposure, while phosphorescence continues after the UV light source is removed.
Even if an HPHT diamond has no measurable fluorescence and contains no phosphorus, it can still have phosphorescence.
As part of our QC inspection, we expose all HPHT diamonds to UV light in total darkness. The diamond on the far left is a 3.12ct D VS1, the diamond in the middle is a 4.10ct D VVS1 round, and the diamond on the right is a 4.12ct E VVS1. All were produced by the same grower.
Upon turning off the UV light, the diamond on the far left showed no phosphorescence. The diamond in the middle showed faint phosphorescence (acceptable at Ada Diamonds), and the diamond on the right exhibited strong phosphorescence. The diamond on the far right failed our quality control.
The Bottom Line
Not all lab diamonds are created equal, even those with the same 4Cs.
Two diamonds can share identical grades on paper and look entirely different in person. That’s why at Ada, we never purchase a diamond sight unseen. Every diamond in our inventory has received a rigorous in-person inspection by a lab diamond expert.
It’s also why we stand behind every stone we offer. With trade-in and upgrade options, you can move forward with confidence, knowing your diamond was chosen to be right not just on paper, but in real life.
At Ada Diamonds, we do not offer lab diamonds with blue nuance or long-wave phosphorescence.
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Blue Nuance & Phosphorescence in Lab Diamonds
Everything you need to know about blue nuance and phosphorescence before purchasing a lab grown diamond.
Diamond Education
What is blue nuance?
Blue nuance refers to a subtle blue color tinge that can appear in HPHT diamonds due to the presence of boron introduced during the growth process. Lab diamonds with measurable boron are classified as Type IIb rather than Type IIa.
An HPHT grown emerald cut with blue nuance. This diamond received an H color grading from IGI.
A CVD grown emerald cut without blue nuance. This diamond received an H color grading from IGI.
How does blue nuance occur?
Boron is sometimes introduced during HPHT diamond growth to help offset nitrogen. Once present, it is difficult and costly to remove. Excess boron can indicate a diamond grower is more concerned with speed of growth than with quality.
Do all HPHT diamonds have blue nuance?
No. Many HPHT grown lab diamonds are beautiful, icy white with no blue undertones present. Blue nuance is not listed on a grading report and is typically only identifiable by an in-person inspection. When diamond growth is slower and more carefully controlled, the likelihood of excess boron is reduced. Lab grown diamonds without blue nuance are more difficult and expensive to grow and command higher prices.
How does it present to the naked eye?
Lab diamonds with blue nuance will display an unnatural blueish undertone. Identifying the color can be challenging without experience, but once seen, it is easy to spot. Blue nuance is extremely difficult to spot in v360 videos on e-commerce websites because the color and lighting of the videos can be manipulated to mask blue undertones.
Lab diamonds and mined diamonds are both graded for color culet up. The lab diamond on the left is HPHT grown with blue nuance, the diamond on the right is CVD grown with no boron present.
How does this affect grading?
Lab diamonds, just like mined diamonds, are graded for color face-down, or culet up. Their color is assessed relative to other diamonds and assigned a grade from D to Z.
An HPHT diamond with noticeable blue undertones present will receive a lower color grade than one without them. This is one of many reasons in-person evaluation by a lab diamond expert matters. A diamond can appear different in real life than it does on a grading report, or in a video, and expert review ensures what you choose looks exactly the way it should.
Lab diamond grading reports may also say “blue nuance” in the comments.
What are alternatives to blue nuance?
Some growers introduce titanium or aluminum to offset nitrogen during diamond growth. Excess titanium can leave an HPHT diamond with a gray undertone rather than blue. These gray undertones are difficult to spot in 360 videos online and are not obvious or noted on a grading report.
How does this affect the diamond other than color?
The presence of boron can make a lab diamond electrically conductive. As a result, some lower-quality diamond testers may incorrectly identify a lab diamond as moissanite.
Boron can also cause phosphorescence, where the diamond emits a visible orange glow after exposure to UV light.
Shining a UV light on an HPHT lab diamond in darkness can expose phosphorescence.
An HPHT diamond with strong phosphorescence will glow orange once you turn the UV light off.
What is phosphorescence?
Phosphorescence occurs in type IIb lab diamonds as a light blue or orange glow after exposure to UV light. The glow can last a few seconds to several minutes.
Phosphorescence is related to fluorescence, but not the same. Fluorescence is a quality that is visible only during UV exposure, while phosphorescence continues after the UV light source is removed.
Even if an HPHT diamond has no measurable fluorescence and contains no phosphorus, it can still have phosphorescence.
As part of our QC inspection, we expose all HPHT diamonds to UV light in total darkness. The diamond on the far left is a 3.12ct D VS1, the diamond in the middle is a 4.10ct D VVS1 round, and the diamond on the right is a 4.12ct E VVS1. All were produced by the same grower.
Upon turning off the UV light, the diamond on the far left showed no phosphorescence. The diamond in the middle showed faint phosphorescence (acceptable at Ada Diamonds), and the diamond on the right exhibited strong phosphorescence. The diamond on the far right failed our quality control.
The Bottom Line
Not all lab diamonds are created equal, even those with the same 4Cs.
Two diamonds can share identical grades on paper and look entirely different in person. That’s why at Ada, we never purchase a diamond sight unseen. Every diamond in our inventory has received a rigorous in-person inspection by a lab diamond expert.
It’s also why we stand behind every stone we offer. With trade-in and upgrade options, you can move forward with confidence, knowing your diamond was chosen to be right not just on paper, but in real life.
At Ada Diamonds, we do not offer lab diamonds with blue nuance or long-wave phosphorescence.