Established in 1931 and based in the United States, GIA is the world’s largest and one of the most respected non-profit institutes of gemological research and learning.  Conceived more than 75 years ago in the grand tradition of Europe’s most respected institutes, GIA discovers (through GIA Research), imparts (through GIA Education) and applies (through GIA Laboratories and GIA Instruments) gemological knowledge to ensure and foster the public trust in diamonds, coloured gem stones and jewellery.

With 1,100 employees, the Institute’s scientists, diamond graders and educators are regarded, collectively, as one of the world’s foremost authorities in gemology.

GIA is the creator of the famous 4Cs of diamond value (colour, clarity, cut and carat weight).  Today, GIA’s D-Z colour-grading scale and GIA’s Flawless-I3 clarity-grading scale are recognised by virtually every professional jeweller and savvy diamond buyer in the world.  The Institute is also known for having developed and patented the first modern jeweller’s loupe.

Internationally, the Institute has distinguished itself as the preeminent source of gemological knowledge and professionalism.  By extension, a GIA diamond certificate is considered one of the world’s premier gemological credentials.  Diamonds of all shapes and sizes are sent to the Institute from every corner of the globe for analysis and grading.

Fluorescence is the visible emission of light which occurs when a diamond is exposed to ultraviolet light. It is a natural characteristic, observed in nearly one-third of all gem-grade diamonds, resulting from the presence of trace amounts of Nitrogen, a common impurity in diamonds.

The most common fluorescence colour observed in diamonds is blue, although other colours are possible, such as yellow, white, green and very rarely orange and red. In diamond certificates, fluorescence is usually classified as None, Faint, Medium, Strong or Very Strong.

Many people are falsely led to believe that fluorescence is a negative quality, when in fact it can have either a positive or a negative effect on the colour and overall look of diamonds. Diamonds with high colour gradings of D, E and F, exhibiting medium to strong fluorescence, can often look somewhat hazy or ‘oily’ in direct sunlight. However, those with relatively low colour gradings, around I or J, usually appear one or two grades better in colour due to the masking effect of blue fluorescence.

The effect of fluorescence on the value of a diamond depends entirely upon its strength and colour. The stronger the fluorescence the greater the negative effect can be on the value of higher colour grades and conversely, the greater the positive effect on the value of lower colour grades. The value of higher colour grades can be discounted by as much as 5% to 10% and the value of lower colour grades can be increased by a similar amount. Weak or faint fluorescence tends to have little or no effect on value.