150 Ashley Road, Hale,

Cheshire, WA15 9SA

0161 233 9977


Third Floor, St Johns Court, 19B Quay Street,

Manchester, M3 3HN

0800 080 3535


5 St Christopher’s Pl, Marylebone,

London, W1U 1NA

020 33 271 271

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Fluorescence Grading

We believe the most important factor when buying a diamond engagement ring is having extensive knowledge and understanding of all aspects. Discover how diamond fluorescence affects the beauty and price of the stone.


Fluorescence does not affect the colour grade, but is a characteristic worth keeping in mind when choosing a diamond. We recommend purchasing diamonds with either None or Faint fluorescence. Under ultraviolet or strong sunlight, Medium, Strong and Very Strong fluorescence can make some diamonds appear to have a slightly blue or milky white tint.

What Is Diamond Fluorescence?

Fluorescence in diamonds is very rare and refers to how diamonds respond when subjected to ultra-violet light. In most cases, diamonds with fluorescence would glow in blue and in rarer occasions in white, yellow or green. While some characteristics such as clarity are desired and can increase the price of a diamond engagement ring, fluorescence decreases the price, just as an inclusion does. Despite this, fluorescence in diamonds can make them appear whiter and closer to colourless. Blue fluorescent colouring can improve the colour of a diamond by a grade or two, whilst reducing the cost.

Learn About Diamond Fluorescence Learn About Diamond Fluorescence
Diamond Fluorescence

Diamond fluorescence is generally considered acceptable in diamonds from grades G to J as it improves the colouring and reduces the cost. Fluorescence in a diamond from grades D – F can make the stone opaque and poorly polished and these negative attributes can outweigh the benefits. However, even with distinct or strong fluorescence this is extremely rare.

Diamond Fluorescence

Impact Of Diamond Fluorescence

Fluorescence found in diamonds from grades K to M can increase the price of the diamond, largely due to the fact that these diamonds possess a faint yellow colour – in this instance the blue fluorescence counter balances the yellow colour and makes the diamond appear whiter. The level of fluorescence in a diamond should be reported on the diamond certification. Levels of fluorescence that occur in diamonds are described on the GIA diamond certification report as: None, Faint, Medium, Strong and Very Strong.

Although diamond fluorescence can be seen as a negative attribute and can decrease the cost of the stone, this rarely affects its beauty or its desirability.

Diamonds graded as Faint will not be negatively affected, largely due to the fact that fluorescence can be very hard to detect. Even for Medium graded diamonds, the effects of fluorescence are very unlikely to detract from the beauty of the stone. Most Faint and Medium graded diamonds can confidently be used to create a truly stunning diamond engagement or wedding rings.