In this age of fakes and copies, all consumers have to keep their eyes open. After all, it is so easy to fall prey to unscrupulous comrades and get something of lesser quality instead of the coveted luxury product. This applies to all spheres, including jewelry. So, let us remain vigilant and doubt everything.
An experienced jewelry connoisseur always scrutinizes the characteristics of the jewelry and will be wary if he reads that the stones in it are ennobled. Isn’t it a fake? What is behind the name “clarified diamonds”? Are they diamonds or just another synthetic clone? And if diamonds are real, how are they ennobled and, most importantly, why? Let’s get to the bottom of it.
Fig.1. On the left – a polished diamond, on the right – a natural diamond
What is a clarified diamond
Nature, like any craftsman, can also make mistakes, and sometimes its creations are imperfect. From the human point of view, of course. Thus, about a quarter of all gem diamonds mined in the world have rather modest characteristics. Modern technology has changed everything. But let’s go in order.
Let us remind you that gemstones are characterized by 4 parameters:
Purely technically, it is possible to improve the first three of them. But a diamond that has undergone re-cutting is not considered to be ennobled. These include only diamonds that a person “helped” to become clearer or change their hue – improved clarity or color. This is an officially permissible procedure, and it has nothing to do with fraud and fakes. Some people will remember how in the olden days old animals were “ennobled” in order to sell them for a higher price and pass them off as young ones. But with diamonds it is a completely different story.
Moreover, this history (improving the appearance and characteristics of precious stones) is already thousands of years old. Remember, for example, heat treatment of amethysts, pink topazes, which do not exist in nature, and which are obtained by heating, soaking emeralds in oil, smoking opals, and others.
Swiss professor Edouard Gueblo said that he sees no reason why man should not improve the creations of nature, if it has not fully completed its work. That is, even the world-famous scientist and gem specialist has nothing against making low-grade diamonds more perfect.
The more so that ennobled diamonds are much (sometimes twice) cheaper than gems on which nature worked more diligently. This means that those who dreamed of owning a diamond ring have an opportunity to realize their dream. In this case, the stone in the jewelry will be of decent size, and, most importantly, natural and natural. That is, not grown in a laboratory, but millions of years underground and found in diamond mines. Jewelry with such gems is a great opportunity to replenish your jewelry closet without sensitive spending. And now let’s learn more about how exactly diamonds are refined.
Color Enhancement
The percentage of colored stones in the world diamond production is vanishingly small – natural minerals are most often colorless or with yellowish tints. At the same time, the demand for fancy stones is very high. And demand, as they say, gives birth to supply. There are two main ways of changing the shade of a diamond or even giving it a new color – irradiation and HTHP methodology. Let’s start with the first one.
Artificial irradiation (irradiation)
The technology involves irradiation of a gem (usually colored diamonds with 7-8 color groups on the Russian scale) with radioactive waves in a laboratory nuclear reactor or an electron gas pedal. Ionizing radiation changes the crystal lattice of the stone, forcing the electrons in it to change their positions. Depending on the duration and intensity of irradiation, the color of the stone can change from light green or green-blue to black with a greenish tint.
To obtain diamonds of fancy colors, irradiated rough is subjected to annealing. Heating changes the optical absorption spectrum, and the color of the mineral is transformed into golden, amber, pink, purple, red-brown, emerald, blue-green and others.
Basic irradiation techniques:
Due to the fact that the overwhelming number of these methods causes only a superficial change in the color of the diamond, irradiation techniques are applied only to cut stones. By the way, man borrowed the irradiation technique from nature. It is known that centuries of diamond staying near radioactive elements and exposure to alpha, beta and gamma rays distorts the crystal lattice of the mineral. This is how the rarest green diamonds are obtained, the brightest representative of which is the legendary Dresden green diamond.
The technology of artificial irradiation was applied by man for the first time in 1904. The experiment was conducted by English chemist and physicist Sir William Crookes, who irradiated the stone with a source based on radium salts, which caused the gem to turn dark green. At the same time, the mineral itself became a source of powerful radiation, so it was impossible to wear it in the future. Modern irradiation technologies are safe for the future owner of the jewelry, because they do not leave residual radiation on the stone.
At the same time, stones whose color has been artificially changed differ from the natural ones. For example, blue minerals have reduced electrical conductivity, and diamonds that have passed through the cyclotron have an “umbrella effect” – the pattern around the calette resembles an open umbrella. There are other differences as well. However, they can be seen only in the laboratory, with special equipment and using spectral analysis methods.
Color modification using the HPHT method
The HPHT (High Pressures – High Temperature) method is intended for brightening stones. This technology is applicable not only to faceted gems, but also to untreated ones, and after modification minerals do not return to their original state under any circumstances.
The technology was invented by General Electric at the end of the last century, in 1999. The method consists in pressurizing the diamond with 70 thousand atmospheres at temperatures up to 2 thousand degrees – these are approximately the conditions under which diamonds grow in the subsurface. During thermobaric exposure, the physical and chemical properties of the stone change: twins dissolve, internal stress areas and structural defects disappear.
With the help of the method it is possible to completely discolor the stone, removing yellow shades, or significantly weaken the cognac color. The method is optimal for stones of the rare type Iia, and makes it possible to obtain diamonds of the purest water. Minerals of the Ia, Ib types are also sometimes suitable for thermobaric treatment, but the highest color values cannot be achieved even with its help.
“General Electric marks diamonds modified according to its method with a laser mark GE POL (an abbreviation of the partner company Pegasus Overseas Ltd.) on the girdle.
In addition, a GIA certificate is mandatory for such diamonds, stating that the stone has been modified.
How diamonds are made clean
Less than half of all mined diamonds can boast of high clarity. The rest have defects and inclusions. GIA identifies many types of defects and inclusions, which are obtained both in the process of formation and growth of the diamond and due to the jeweler’s error. Recall that diamonds without defects and those in which minor imperfections are visible only under 10x magnification are considered flawless in terms of clarity. It is these diamonds that have the highest value.
However, clarity defects are not a verdict for a gem. With the help of “cosmetic” procedures, a diamond can become much cleaner and sparkle in such a way that no one would suspect a natural “flaw” in this splendor. How do diamonds become cleaner?
Laser drilling
The last century was a century of scientific breakthroughs. New technologies and materials appeared in all spheres of human existence. It also touched the jewelry niche. About 60 years ago, a technology was invented that allows improving the optical characteristics of stones by removing dark inclusions (magnetite, pyrrhotite, pentlandite and others). The technique was called laser drilling – “laser drilling of diamond”.
The essence of the technology is laser drilling a hole in the stone with a diameter of tenths of millimeters to gain access to the inclusion. Then through the hole is introduced a reagent that dissolves or bleaches the dark area, and after the channel from the laser is filled with a special material whose optical properties correspond to diamond. In this case, the diamond does not add or decrease in weight, which is confirmed by the GIA, issuing certificates for the gems that have undergone the procedure. Laser treatment can be applied to stones with clarity ranging from VS2 to I3, so not every diamond can be improved in this way. At the same time, it is impossible to notice with the naked eye that the stone has been refined.
This is the traditional method of treating a stone with a laser. Recently, in the 2000s of our century, the ILD method (internal laser drilling with pulsed lasers) appeared. GIA specialists encountered it in February 2000, having found formed channels inside the stone defect, and these channels had no external exit. However, internal laser drilling technology has not been widely used because it is used to remove defects that are close to the surface of the stone.
Fracture healing (“the Yehuda method”)
Foreign inclusions are not the only problem that devalues a diamond. External and internal cracks also relegate stones to the category of low-grade stones. In 1987, Israeli specialist Zvi Yehuda developed a method of removing cracks from diamonds by filling them with a liquid with high refractive properties under a pressure of about 50 atmospheres.
It turned out that with this method it is possible to raise the clarity of diamonds by 1 level – from SI to VS. Unfortunately, although this treatment improves the appearance of the stone, it has a number of disadvantages and does not guarantee the stability of the changes made. That is why neither the GIA nor other reputable gemological laboratories issue certificates for “treated” diamonds.
How to determine that a diamond has been ennobled
As mentioned above, treated diamonds are significantly cheaper than those that are flawless by nature. Moreover, the difference in price between two externally almost identical diamonds can be 50-70%. Therefore, a large stone with a relatively budgetary cost is most likely to be ennobled using one of the above methods.
However, this does not cancel the fact that both twins will be considered absolutely natural stones of natural origin and will receive GIA certificates. The only difference is the obligatory marking in the “passport” of the gem that has undergone physical and chemical treatment. In Russia, there are no strict rules for marking treated diamonds, and therefore one can only find out whether a diamond has been altered or is perfect by nature after a jeweler’s evaluation.
Summary
At the end of the article it is worth summarizing its results and highlighting the main points. So: