Diamond Fluorescence Explained

Quick answer: Diamond fluorescence is a glow, usually blue, that some diamonds give off under ultraviolet (UV) light such as blacklights or strong sunlight. It is graded None, Faint, Medium, Strong and Very Strong. In most diamonds it has no visible effect in normal light; faint to medium blue can even make slightly warm (H to K color) diamonds look whiter. Very strong fluorescence can occasionally make a diamond look hazy, so check it in person or on video for D to G stones.

Fluorescence appears on most grading reports. Here is what it means and whether it matters.

Fluorescence Grades

What Causes Fluorescence?

Trace elements, most often nitrogen, absorb UV light and release it as visible light. Around a quarter to a third of natural diamonds show some fluorescence. Lab grown diamonds usually show none or faint fluorescence, though some CVD stones can glow orange or other colors under specialized light.

Is Fluorescence Good or Bad?

• Good: can offset slight yellow in warmer colors; fun glow under blacklights; natural diamonds with fluorescence can cost less.
• Bad: very strong fluorescence can occasionally cause a hazy look.

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Does Moissanite Fluoresce?

Moissanite typically shows little to no fluorescence. Its sparkle comes from its high refractive index and dispersion. Read why moissanite sparkles.

How to Check Fluorescence

• Look for the grade on the certificate.
• View the stone in daylight and indoor light.
• Ask for videos in natural light for strong or very strong stones.

Quality Stones at Ivevar

We select stones for beauty in real-world light and hand-set them in our Surat workshop. Every piece ships worldwide with free shipping and 30-day easy returns. Browse moissanite earrings and stud earrings.

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Frequently Asked Questions

Is fluorescence bad in a diamond?

Usually not; only very strong fluorescence occasionally causes haze.

What color do diamonds fluoresce?

Most often blue.

Do lab grown diamonds fluoresce?

Usually none or faint.

Can fluorescence make a diamond look whiter?

Faint to medium blue can help H to K colors.

Does fluorescence affect price?

Strong fluorescence can lower natural diamond prices slightly.

The Bottom Line

Fluorescence rarely affects beauty. Focus on cut, color and clarity, and inspect very strong fluorescence stones before buying.

Related Guides

• The 4Cs explained
• IGI vs GIA certificates
• How to tell if a diamond is lab grown

Author Bio

Aumsri Pradhan

Founder, Ivevar Luxury

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Aumsri Pradhan is the founder of Ivevar Luxury, a Surat-based fine jewelry brand that designs and handcrafts lab grown diamond and moissanite jewelry in its own workshop. She leads the brand's design and customer experience, from engagement rings and bridal sets to custom pieces made to each client's story. Through the Ivevar blog, she shares practical guidance on lab grown diamonds, moissanite, diamond grading and ring design to help buyers choose with confidence.

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