The Guide to Colored Diamonds

The 4Cs of diamond grading are Color, Cut, Clarity and Carat. The first of those, Color, is based on how clear or “white” the diamond is, with no color at all actually being the most desirable color. However, there comes a point where diamonds which contain color become desirable. Partly because of the unusual effects they can display, and partly because some colors are extremely rare.

It can be easy to forget that not all diamonds are created equal. As well as white diamonds, other colors include yellow, orange, red, blue, green, pink/purple, brown, grey and black, with the varying degree of color determining how valuable each stone might be. A white stone with a hint of yellow will be considered much less valuable than a pure white diamond, all other things considered, but a “fancy” yellow stone is considered very desirable past a certain point, and this is true for all the colored diamonds.

The specific way in which diamonds are created, with extremes of both pressure and heat being applied to carbon materials means impurities often find their way into the lattice of the minerals, and it is these impurities which largely account for the varying colors that we see. Boron creates blue diamonds, nitrogen those within the yellow part of the spectrum, hydrogen for pink/purple and graphite or sulfides create black diamonds. Radiation can also be a factor, causing the creation of green diamonds. 98% of diamonds are termed as Type Ia which, if contaminants are present, will usually be nitrogen atoms, and this is why we see more white and yellow diamonds than we do any other color.

To distinguish true yellow diamonds from white diamonds with yellow coloring, the prefix “fancy” is applied. All other colored diamonds are simply known under their dominant color name, as these stones don’t tend to have the same degree of graduation in the color changes that yellow diamonds do. We’ve already mentioned that Type Ia diamonds account for 98% of production, and a further 1.8% are Type IIa, which produce fancy yellow, pink/purple, red and brown stones, although very few red diamonds are produced and are considered to be the rarest of all diamonds.

The remaining 0.2% of diamonds are blue, black or green but, whilst also extremely rare, this rarity doesn’t always translate into value especially in the case of black diamonds. Blue diamonds which contain boron (a small number do not) also have the added advantage of being semiconductors (able to conduct electricity) and are used in industrial applications, where all other diamonds are used as insulators as they do not conduct electricity.

The array of colors available make grading such diamonds very difficult. GIA standards range from D (pure white) to Z (yellow), but other colors are also graded according to the depth of color they contain. The problem for anybody making a valuation, is that there are 1780 possible color grades for non-white diamonds, which makes the grading process very subjective. Despite this, diamonds with color are allowed a much wider scope to the color definitions they are given without affecting the value significantly. For example, two purple diamond may be several shades different on the color wheel, but will be graded similarly for valuation purposes.

The value of any commodity is based around supply and demand, and colored diamonds are no exception to this rule. Pure white diamonds are very desirable and therefore very valuable, as are very rare red diamonds, but it should be noted that rarity only goes so far when valuing a diamond for sale. A good example is black diamonds which, although rare, don’t fetch the same high price which some other colors do. Partly this is down to the fact that a black diamond is more unusual than it is attractive, and therefore its application in jewelry manufacture is far more limited than other colors. Compare this with a blue diamond, which is stunning to look at in isolation, and so is equally as stunning when set into a ring.

Another issue for black diamonds is the increasing trade in non-natural stones. Demand for black diamonds has increased over the years, but this has led to heat treated and synthetic diamonds being produced in ever larger numbers, all of which sell for much lower prices than natural black diamonds. This increase in non-natural black diamonds does affect the value of the natural stones somewhat because they suddenly don’t seem as unusual as they once were and so demand, whilst rising, isn’t always confined to natural stones.

Colored diamonds are beautiful, by anybody’s standards, and we too often get caught up in the desire for pure white that we forget the alternatives can be just as appealing.

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