Chemical analysis of gemstones

Chemical analysis of gemstones.

Proper chemical analysis only began to develop in the middle of the 17th century, inter alia under the influence of already known to us Robert Boyle, which established the concept of a chemical element and developed a number of the simplest analytical methods. It was thanks to him and his successors that a series of discoveries of new chemical compounds and - what should be considered much more important - previously unknown chemical elements began. Let's remember, that a year, in which Robert Boyle announced the hypothesis, that ruby ​​and sapphire are the same gemstones, only known 14 elements. Today we know them 109, including many created artificially by 20th century physicists.

The first discovery significant for the chemistry of gemstones was not made until one year 1798. Exactly on the day 15 February 1798 The French chemist Vauquelin announced at a solemn meeting of the French Academy in Paris, that in the emerald he discovered a new chemical element – beryl. It was 32 in order of discovery of the element, and the first one separated from a gemstone. Emeralds have been known for a long time. Already in 1650 years before our era, almost three and a half thousand years before the discovery of beryllium, emeralds were mined in the mines of the Nubian Desert, near the Red Sea. They were the favorite ornaments of Cleopatra, famous for its beauty, and because of its considerable hardness, greater than the hardness of quartz, they were used to carve seals and cameos in other precious and ornamental stones. Roman Emperor Nero, who was nearsighted, used a lens cut from emerald and, as the legend says, through this emerald lens he watched the fire of Rome, set on fire at his command. Color physics tells us, that the red flames seen through the green stone of the emerald must have appeared black, ghostly languages.

Years after the discovery of beryllium it was found, that the emerald is a very complex chemical, beryllium and aluminum silicate (aluminium). Still later it was discovered, that the same compound with practically the same chemical composition is aquamarine – gemstone, like the transparent emerald, but light in color, cyan, completely different from dark green, the deep and lush green of the emeralds. Still later it turned out, that beryllium and aluminum silicates are the same: złotożółty heliodor, pink morganite and colorless goshenite.

Clay was discovered only in 1825 year. Even later, the presumption of Robert Boyle was confirmed, that ruby ​​and sapphire are actually an identical compound-alumina in terms of composition with a very simple chemical formula Al2O3. And again, a story similar to that of the emerald family was repeated. Some colorless and green-colored stones have the same chemical formula, purple etc.. They are all given the common name corundum. The red name remains ruby, and blue, according to the will of the ancients, sapphire. Traditional jewelers also retained the traditional names for corundum of other colors, but to distinguish them from stones, which are more entitled to these names, they added the word "eastern". Thus, as a result of the research of chemists, it appeared: eastern emerald to distinguish green corundum from true emerald, eastern amethyst, eastern topaz and other "eastern stones”. A different rule applies today. Corundums are divided into red rubies and sapphires, the sapphire being blue corundum, and stones with the same chemical formula, but a different color is called sapphires with an additional color specification. So we have white sapphire (leukoszafir), green sapphire, yellow sapphire etc.. With one exception. Very rare sapphires, and at the same time very beautiful, intense red-yellow color, are traditionally called padparadha (from the Sinhala word padparagaya – lotus flower).

Despite the development of chemistry, the development of more and more accurate methods of chemical analysis, answer the question, why is the ruby ​​red, and blue sapphire, it was not found for a long time. During the analyzes it was found, that e.g.. emeralds, aquamarines and other precious stones, apart from the basic ingredients, contain small admixtures of other elements, how: sodium, potassium, lit, rubid i cez. Similarly, corundum can be contaminated with slight admixtures of chromium, titanium or iron, but the small amount of these admixtures did not allow correct conclusions to be drawn. Only modern chemistry and modern very accurate methods of quantitative analysis, allowing to detect even the smallest amounts of additional ingredients, and the experience gained while trying to manufacture gemstones in the laboratories of scientists made it possible to answer the question, what determines the color of the gemstones. A pure co.rund without any impurities is a colorless stone, called white sapphire. Equally pure beryllium aluminum silicate is colorless goshenite. Similarly, colorless rock crystal is unpolluted silicon oxide (SiO2), a chemical known to all of us as sand.