Guides
Fluorescence is how a diamond reacts under ultraviolet light. It is listed on the certificate — and it is not automatically a defect.
Labs describe intensity as None, Faint, Medium, Strong, or Very Strong. Blue is the most common color noted for colorless diamonds.
None and Faint rarely change daytime appearance. Medium can be subtle. Strong and Very Strong deserve a closer look in photo and video.
Blue fluorescence can make a slightly warmer color grade look whiter in some lighting. That is why Medium blue sometimes trades at a discount without looking worse.
Strong fluorescence can also make a stone look hazy or oily in sunlight for some diamonds. That risk is why you never buy Strong fluorescence on grades alone — open the media.
Use the Appearance filters for fluorescence intensity when you want to include or exclude Strong glow. Compare candidates side by side in photos.
If two stones are close in cut, color, and clarity, and one has Medium fluorescence at a better price, the fluorescent stone can be the smarter buy after you check the video.
Carat Mate lists certified loose diamonds for shoppers in the United States, Canada, the UAE, London, and Australia. Prices are in USD everywhere. We ship to the United States, Canada, the UAE, London, and Australia.
