Not necessarily. If your lab-grown diamond has a slight blue tint or blue nuance, that does not automatically mean it is a blue diamond.
A lab-grown diamond can appear blue for several reasons. In some cases, the color comes from the diamond itself. In others, it may be caused by fluorescence, surrounding light, reflections, or the diamond’s fire.
So how can you tell where that blue appearance is actually coming from? Let’s break it down.
Why Can a Lab-Grown Diamond Have a Blue Tint?
Reason 1: Trace Boron May Be Present in HPHT-Grown Diamonds
As we discussed in our guide to how blue diamonds get their color, boron can influence the color of a diamond. A similar effect can sometimes occur in diamonds that are intended to appear colorless.
Lab-grown diamonds are primarily created using two growth methods: HPHT (High Pressure High Temperature) and CVD (Chemical Vapor Deposition).
During the growth of some HPHT lab-grown diamonds, trace amounts of boron may enter the diamond crystal lattice and replace some of the carbon atoms. Boron changes the way the diamond absorbs visible light, which can give the stone a subtle blue or grayish-blue undertone.
In gemological testing, diamonds with detectable amounts of boron may be classified as Type IIb diamonds. However, being Type IIb does not necessarily mean that a diamond will look visibly blue. In some diamonds, the amount of boron is so small that it can be detected with specialized equipment but has little or no noticeable effect on appearance.
This type of blue nuance is more commonly associated with HPHT-grown diamonds. If minimizing a boron-related blue undertone is especially important to you, you may want to consider a Type IIa diamond.
That said, the growth method alone should not determine your choice. A diamond should ultimately be evaluated based on how it actually looks rather than simply whether it was grown using HPHT or CVD.
Reason 2: The Diamond Has Blue Fluorescence
Diamond fluorescence is the visible glow that some diamonds produce when exposed to ultraviolet (UV) light. Blue is one of the most common fluorescence colors seen in diamonds.
However, blue fluorescence and a blue body color are not the same thing.
A diamond that shows blue fluorescence is not automatically a blue diamond. Likewise, a diamond with little or no noticeable fluorescence can still appear slightly blue for other reasons.
If your diamond grading report includes a Fluorescence grade, you can use it as one piece of information when evaluating the stone. However, fluorescence alone cannot tell you whether a lab-grown diamond has a true blue nuance.
Blue Caused by Lighting, Reflections, and Diamond Fire
Sometimes, what looks like a blue tint is simply an optical effect rather than the diamond’s actual color.
Diamonds are highly reflective. Because of this, colors from the surrounding environment can appear across their facets.
A blue sky, cool-toned lighting, blue clothing, nearby objects, or even a phone camera’s white balance can make an otherwise colorless diamond look noticeably cooler or slightly blue in photos—or even to the naked eye.
What Is Diamond Fire?
When white light enters a diamond, dispersion separates the light into different visible colors.
As the diamond, light source, or viewing angle changes, you may see brief flashes of red, orange, yellow, green, blue, and other colors. These colorful flashes are known as diamond fire.
Can Diamond Fire Make a Diamond Look Blue?
Yes, and this is one reason diamond fire can sometimes be confused with a blue nuance.
If the blue appears only briefly on certain facets or at certain angles—and disappears as you move the diamond or change the light—it is most likely part of the diamond’s fire rather than its actual body color.
A true blue undertone behaves differently. If a diamond continues to show a relatively consistent blue or grayish-blue tint under neutral lighting and from multiple viewing angles, it may be worth taking a closer look at whether the color comes from the diamond itself.
How Can You Tell Why Your Diamond Looks Blue?
Start by cleaning the diamond so that oils and residue do not affect its appearance. Place it against a white or neutral background and examine it under soft, neutral white light.
Then gently rotate the diamond and look at it again in a different lighting environment.
Pay attention to these three things:
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The blue appears only as a quick flash on certain facets:
It is more likely diamond fire. - The blue changes with the surroundings, lighting, or viewing angle: It is more likely caused by environmental reflections.
- A blue or grayish-blue undertone remains visible under different neutral lighting conditions and from multiple angles: The diamond may have a true blue nuance, and further evaluation may be helpful.
A diamond that looks blue in one photo or under one particular light is not automatically a blue diamond. The most important clue is whether that color remains relatively consistent under neutral lighting and from different viewing angles.
