G colour diamondFascinated by coloured stones, I had long neglected highly symbolic solitaires until the day I discovered the coloured diamond. I was working in London at the time and the visit to a Exhibition diamond exhibition organised by the Argyle mine in Australia changed my view of diamonds forever...

The other event that counted for me was a lecture by diamond dealer Gabi Tolkowsky. Listening to this man talk about diamonds is captivating and allows one to understand that this phenomenal stone, far from being reduced to an unsurpassable brilliance and a price that is just as much, can become a work of art in the hands of an artist and mathematician. Gabi Tolkowsky has spent her life inventing new sizes with beautiful names: Dahlia, Marigold or "Gabrielle" a marvel of 105 facets. 105 facets, on such a small volume, what precision! Almost twice as many facets as in the modern "brilliant" cut, developed by his great-uncle Marcel, at the beginning of the 20th century... Will I ever be able to contemplate a stone cut by Gabi?

Diamond cut Gabrielle by Gabi Tolkowsky

But back to the diamond. This blog has no intention of competing with the many articles available on the internet. I will therefore do as I do with my students: extract the 3 or 4 essential notions that it is essential to know.


1. Origin

Diamond, an element composed of pure carbon (C), was formed on earth more than 600 million years ago (often 1 to 2 billion). It comes from the depths of the planet, (more than 150 kilometers and up to 1000 kms), where the magma is subjected to very high temperature and pressure conditions. The diamond goes up by chimneys of volcanoes. Only diamonds that have travelled fast enough (2000 km/h) have survived this perilous journey. Once on the surface of the globe, erosion breaks up the rocks and carries the diamond crystals into rivers and sometimes into the sea. In addition to "terrestrial" diamonds, very rare and mostly tiny specimens (nano diamonds) have been found in meteorites.

2. Price formation, the 4 Cs

The "white" diamond is the only gemstone for which there is a world price. The price is based on relatively objective criteria of colour, clarity, quality of the cut / proportions and weight. (The 4 Cs: Colour, clarity, cut, carat).

  • Colour, the colour of white diamonds is graded from "D", the rarest, an exceptional white to "Z" (yellow grey),
  • Clarity, the purity, from "IF" (for Internally Flawless) or pure at 10x magnification to "P3" (pitted with many inclusions),
  • Cut, the quality of the cut, measures the respect of the proportions, the angles, the thickness of the roundel, the symmetry and the polish...
  • Carat, meaning the weight, in carats. The carat is equivalent to 0.20 grams.

The price is generally given by carat and it increases mechanically with the weight because, for the same quality, the increase in weight is a factor of rarity. So a diamond twice as big as another, can be worth 3 to 4 times more, for the same quality.

The "brilliant" cut, round, is the most common. A "modern" brilliant is cut in 57 facets and a 1 carat stone measures 6mm in diameter.

As for its color, the non-professional eye begins to distinguish the change in hue after 5 gradations. The price of a 1 carat stone may have dropped by about 30% in the meantime.
G and L colored diamond
The 1er diamond is colour G white extra, the 2ème is "L", slightly tinted.

Examples of prices given by our diamond dealer.

Diamond Price Chart

These characteristics are announced by the professional, they can also be attested by a certificate. However, the whole personality of a diamond cannot be summarized by a few measurements. Each stone plays with the light in a distinct way and the great professionals are not amateurs of certificate. When one chooses a stone with confidence, one must also trust one's eye, tame the light and let oneself be charmed, without necessarily choosing the stone with the best characteristics, especially since for such a setting or such a type of jewel, the best colour may prevail, whereas for another jewel, it is the purity or the quality of the cut that will prevail.

Niessing solitaire ring, diamond LA slightly yellow diamond will see its colour "absorbed" in a yellow gold jewel, while a platinum or white gold setting will magnify the whitest diamonds. The diamond in this photo is L coloured... Who would have thought it? The client preferred to focus on purity.

3. Hardness and strength

The diamond (adamas) takes its name from the Greek "Adamas" which means invincible. This is a huge misunderstanding. Its hardness, the highest in the whole universe, is a resistance to scratching, thus to cutting and polishing. A diamond can only be scratched by another diamond, but this is no insurance against breakage, which is relatively easy sometimes! So beware of shocks! And, of course, the diamond, carbon, burns as long as the flame is bright enough and lasts long enough.

"A diamond is forever", the famous advertising motto coined by the De Beers advertising agency in 1947, is a powerful message that has largely penetrated the minds of many couples who would not consider celebrating their love otherwise... While it may be dreamt of as the sublime symbol of a love, or as a very worthy symbol of it being passed from generation to generation, it is still necessary to take care of it... as well as of the person loved.

4. Coloured diamonds

The diamond exists in all the colors until the black, in a natural way. But, with the exception of champagne to brown or black, coloured diamonds (daffodil yellow, pink, red, green, or blue) are more expensive than colourless diamonds (called white).

Sometimes a bad grey-yellow colour can be modified by an irradiation treatment. In France, the invoice mentions these treatments and the price must be lower.

Below, pink, brown and yellow diamonds of natural color (stones of about 0.02 carat, brilliant cut).
Natural diamonds, pink, brown, yellowThe diamond on display:

At the gallery, we have dedicated several exhibitions to diamonds. In 2018, we exhibited Niessing's latest creations with some very surprising Tension rings. In 2015, we organized a very playful Exhibition , entitled "The diamond plays hide and seek". There was no shortage of hiding places! They ranged from tone-on-tone camouflage, through the rough diamond, which does not shine, rings with diamonds that run around the finger, placed underneath, inside, sideways but not where you expect them and finally a diamond hidden in the middle of stones that are so shiny but are not!