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Most natural green diamonds will be on the upper end of the value scale. The prices of green diamonds are similar to those of pinks. Pure green diamonds are so rare in nature that very seldom will the value of a green slide down the scale.
What makes a diamond green?
Green colour in diamonds is caused by vacancies within the crystal structure which are created when carbon atoms are dislocated by high speed atomic particles. Radiation, either natural or artificial, can cause this effect, although it only penetrates a short distance into the stone, giving it a green skin.
This ‘vacancy’ causes a vibronic colour centre, which absorbs light from the red area of the spectrum, with the notable line being at 741nm. However, some natural diamonds possess a bottle green colour which isn’t associated with any known colour centre.
The visibility of a green hue suggests that a diamond has spent a few million years being bombarded by radioactive materials (note that hydrogen may also be the cause in some yellowish-green stones). The reason that a true green diamond is so valuable is that radiation does not usually affect the entire gem. This means that most green diamonds are only green on the surface. Their beauty is therefore considered as skin deep. If the green colour of a diamond is only skin deep, the green colour may disappear under the slightest of changes and is likely to disappear during the faceting process. However, if the diamond has been through barrages of beta and gamma rays as well as neutrons and remained green, the chances are that its green beauty comes from within. In these rare instances, it will still look green regardless of the cutting and polishing process. Most stones in the green family come from Brazil, Venezuela and Zimbabwe. Natural green diamonds are extremely rare and desirable. The beauty of these gems has spawned unprecedented desire and unparalleled prices among collectors and connoisseurs.
When processed, most of the stones that appear green in nature end up as white diamonds or light yellow diamonds (sometimes referred to as silvery Capes). If a brown coloration patch appears naturally in a green diamond, the GIA recommends that the patches be left visible because they indicate that the diamond is ''naturally'' green and has not undergone any irradiation treatment such as artificial colouring. Hence, the brown patch does not affect the price of the stone in any way.
Like all natural coloured diamonds, green diamonds are often graded as having colour modifiers. Bluish-green, yellow-green and blue-green are just some of the combinations recorded. However, traces of grey, yellow or brown in a green diamond can result in a significant price drop.
A pure green colour diamond can be found with eight different colour intensity grades. These are faint green, very light green, light green, fancy light green, fancy green, fancy intense, fancy vivid, and fancy deep. Green colour diamonds can be found with a single, pure colour, but most often contain one or even two secondary hues. The various overtone colours of a green diamond are yellow, yellowish, blue, bluish, brown, brownish, grey, greyish, grey-yellowish, and greyish yellowish.
Fancy Light yellow Green Emerald Cut Loose Diamond