yellow-diamonds

 

We are going to show you what to look for in beautiful yellow diamonds – many of which come from the Ellendale mine – near the argyle mine in west Australia.

 

 

Diamonds come in many colours and Natural yellow diamonds have a tiny bit of Nitrogen. We call Yellow diamond a "fancy colour” when it’s off  the colourless diamond scale.

 

We grade Colourless D to Z yellow tinted diamonds thru the side in the face-down position, yet fancy colour diamonds are graded by Labs from the face-up.
 

Yellow diamonds are deemed "fancy" when a stone displays more colour than the "Z" colour grade based on the GIA D-Z colour grade scale. Why? Because it makes more sense, and really, all diamonds should be graded for their face up colour. But it is much harder to do.

Light-colours

 

Fancy Colour Terms on Grading Report Terminology:

Fancy yellow diamond grades issued by labs start at Fancy Light, Fancy, Fancy Intense, Fancy Dark, Fancy Deep, Fancy Vivid

 

Very rare colours in diamonds (like pink, blue and green) can receive these 3 lower grades: Faint, Very Light and Light - because there is a market for them and they fetch high prices.

 

The diamond on the far left below is ‘Fancy Light Yellow’ (FLY). The diamond on the far right is a ‘Fancy Vivid Yellow’ (FVY) yellow (note the two ugly dark zones – at Holloway Diamonds we avoid this). The two centre diamonds are both ‘Fancy Intense Yellow’, or ‘FIY’.

 

Note FIY has a very broad range and the price comparison is broad too; like comparing the range of D to I in colourless diamonds; 50% price variations are common, so even comparison shopping in person is hard unless you have some comparative sample. Comparisons online are impossible.

yellow-grades

 

Diamond colour graders at the Gemological Institute of America (or GIA) have the tough job of making grade the calls - they evaluate each diamond for hue, tone, and saturation in controlled lighting boxes like that used to judge fabric colours. They are not always considered to be consistent, but they are the best there is in an imperfect world.

Munsell-colour-wheel

 

Hue- A diamond's overall body colour e.g. orangish yellow, yellow, greenish yellow

 

Tone - A diamond's lightness or darkness

 

Saturation - The intensity or saturation of colour

 

This is the Munsell colour wheel that shows how Hue, Tone and Saturation work together.

 

colour-identifiers

 

This chart from OctoNus shows dots of various Munsell colour identifiers and the boundaries for each grade.

 

Secondary or modifying colours impact the hue of the fancy colour.

 

A yellow diamond with a green secondary hue is graded as "Fancy Greenish Yellow." A blue diamond may have a grey secondary colour, and will be graded as "Fancy Greyish Blue" and so on. Secondary colours in yellow diamonds include greenish yellow (more expensive), brownish yellow (less expensive), and orangish yellow (can be very expensive – pure orange is very rare).

Extinction or Dark Zones

extinction

 

At Holloway Diamonds we reject most fancy yellow diamonds on the market because they have ugly dark zones as a result of bad cutting.

GIA have a line on the certificate that refers to the even-ness of colour distribution. To get this grade the stone has to be really ugly with more than half the stone having dark zones of extinction or light leakage which will appear dark once the diamond is set. These photo’s are from the GIA’s journal.

dark-zones

 

However most fancy yellow diamonds, like these photo’s I took from the Internet, are not bad enough to get the ‘uneven’ grade, but the dark zones are persistent ugly patches – sadly typical of most fancy yellow diamonds.

 

The science of cutting fancy coloured diamonds is a very different to cutting colourless diamonds where contrast from dark zones is what makes them sparkly and brilliant – the alternating bright dark bright flashes as you rock a white diamond.  If a diamond has a dark zone in a photo then it probably will in real life too, and light leakage zones always appear dark once the diamond is set.

 

Compare our diamonds in person with what you see in other stores and you will see for yourself how common dark zones are and why fancy yellow diamonds with areas of extinction and light leakage are less attractive.

 

We are proud of our fancy yellow diamonds that are cut and polished by master cutters using scientific processes,
the development of which I have personally been involved in.

www.octonus.com/oct/projects/fancycolor.phtm

 

Fluorescence and Complementary Colours

Colours directly opposite each other on the colour wheel are said to be ‘complementary colours’.
Blue and yellow are complementary colours; red and cyan are complementary; and so are green and magenta.

 

Mixing together two complementary colours of light gives you white. So adding blue fluorescence can make a
yellow diamond paler. Yellow diamonds that fluoresce yellow will be a stronger yellow in daylight which has more
UV light. Unfortunately, many yellow diamonds actually fluoresce blue and one of the things we do is ensure that
our diamonds do not lose too much colour if they are fluorescent. You can see a demo of this in the video.