If you are endowed with a healthy dose of curiosity, you will love precious stones. Each one conceals its own unique secrets, secrets the stones can be coaxed into revealing. Before Mother Nature creates something so beautiful, numerous coincidences must first occur deep within the earth. Natural forces such as high temperatures and extreme pres- sures can transform ordinary substances into precious crystals. Though created under the most arduous conditions below the surface, each crystal still faces a long journey to be- come a polished stone and an eye-catching jewel. Diamonds are prized because of their lack of colour, but the appeal of coloured gems lies within their infinite variety of hues. Whether in delicate pastels or vibrantly lush tones, they lend wings to their beholder’s imagination. Do you prefer the yellowish green of lemon citrine, the mysterious purple of amethyst, or the fiery gleam of imperial topaz? Decide for yourself which stone is your favorite – and become part of a never-ending story. In addition to gemstones’ rarity and naturalness, it is also their longevity that has perennially bewitched their beholders.
It is not easy for the inexperienced to cor- rectly appraise the value of coloured gem- stones. Even specialists require years of practice and a trained eye, especially since there are no standards as for diamonds. On the following pages, we would like to intro- duce you to the most important quality cri- teria such as colour and transparency. The value of a gemstone is further augmented by a combination of beauty and rarity. A per- fect example can be found here in the neon blue colour of this paraiba, a member of the tourmaline family.
A fine gem’s colour is one of its most important elements, but it is also one of the most subjective factors. Coloured gemstones are highly diverse, and so too are the moods they can evoke. Orange stands for optimism, yellow for cheerfulness, green for generosity, red for love, and blue for fidelity. The more unusual a colour is, the more ardent- ly people strive to find words to describe its beauty. Imagine a tourmaline that is as blue as a swimming pool, a topaz with a golden gleam that rivals the sun, or an eme- rald with the verdant hues of a lush garden. Intoxicating as these colours may be, they in fact result from a sober natu- ral process and the gem’s chemical composition. Metals and their compounds are the principal sources of colour in the mineral kingdom. Iron, for example, imbues sapphires with incomparable blueness and chrome gives rubies their redness. The slightest nuances of colour can decisively influence a gem’s value. Furthermore, rare and especially coveted variations exist for nearly every type of gemstone – variations such as the red rhodolite (a special type of garnet) or the pink rubellite, which belongs to the tourmaline family.
Careful scrutiny can uncover tiny inclusions of mine- rals or foreign crystals in nearly every coloured gem- stone. Sometimes known as “Mother Nature’s finger- prints,” such traces of growth are infallible signs of the authenticity and naturalness of a coloured gem- stone. As a general rule, the more transparent a gem- stone is, the more valuable it is since a gem’s vitality and luminosity result from its transparency.
The rarity and the provenance
That which is rare, is avidly sought. A good example of this is the red ruby, which ranks among the world’s most precious stones. Alongside rarity, the country of origin is another factor determining a stone’s value since colour varies with the the gem’s location and specific constituents. The best emeralds, for example, featuring an incomparably intense and slightly bluish green colour, are often found only in Colombia. The rarest imperial topaz, whose honey-coloured hue is a real highlight, usually comes from the region around Minas Gerais in Brazil, which is justly famed for its choice topazes.
Weight and the cut
The carat has served as the unit of measure for the weight of pre- cious stones since classical antiquity. One carat is equal to 0.2 grams, which is the exact weight of a single carob seed, a so- called qirat. Each qirat is identical in size and weight, which led them to be used as reliable units of measure. A gemstone-cutter decides on a particular cut depending upon the weight, composi- tion, and colour of the unprocessed stone. Only a perfect cut can fully reveal a gem’s inherent brilliance and liveliness. Unlike dia- monds, whose cuts are based on mathematical calculations, coloured stones are cut on the basis of experience and instinct.
A smooth cabochon cut is usually the best choice for a stone that is not entirely transparent, such as the red tourmaline found in the photo at right. A large number of facets can help produce diverse refractions of light and a sparkling firework of colours in more transparent gems.
The Mohs scale of hardness, developed more than 150 years ago by Viennese mineralogist Friedrich Mohs to measure the hardness of minerals, is still in use today. Mohs arranged minerals on a scale of 1 to 10 accord- ing to their hardness. The diamond, a jewel of incom- parable beauty, ranks at the top of Mohs’s scale with a hardness of 10. Generally, a harder stone can scratch a softer one, but stones of equal hardness cannot scratch each other. Corundum (e.g., sapphire and ruby) has a hardness of 9 on Mohs’s scale. The lower end of the gemstone scale is represented by a hard- ness of 6 where moonstones, for example, can be found. Softer stones gradually lose their gleam be- cause they have no resistance to the abrasive effects of miniscule particles of quartz (7 on the scale) circulating in the air and settling onto polishing cloths. Hardness is also an important factor for gemstone- cutters, who must have many years of experience under their belts in order to properly appraise a stone, especially since several crystalline surfaces on one and the same gem can differ in hardness.
The aquamarine and the heliodor
Aquamarine means “water of the sea” – and anyone contemplating one of these gems belonging to the beryl family will understand the meaning of this name. Alongside its fascinating look, the aquama- rine’s blue hue promises fidelity, honesty, and a happy marriage. Nothing remains hidden from someone who peers through a beryl as this stone’s name originates in the same root as “Brille,” the German word for eyeglasses. Nero, the infamous Roman emperor, observed duelling gladiators through a beryl to augment his vision. Most beryls come from Brazil, as does the heliodor, a yellow- ish green variety of the gem. Derived from the Greek language, its name means “gift of the sun.”
The emerald and the sapphire
Intensive and sublime is the green of the emerald, the most precious of all beryls. Its tiny inclusions are described with the word “jardin,” French for “garden.” The emerald shares some of its strong aura with those who feel weak: this gem is believ- ed to imbue its wearer with strength, courage, and happiness. The sapphire, which belongs to the corundum family, has a similarly powerful appeal. Its pale blue variation comes from Sri Lanka, whence the name “Ceylon sapphire,” while the dark blue variant is mined in Burma. The most precious sapphires with their silky cornflower- blue hues are found in Kashmir.
Gaze upward at the blue sky on a cloudless summer day and you will feel as though you are peering into the depths of a blue topaz. These gems are radiant in fresh azure, pastel Swiss, or rich London blue. Natural topaz combines the utmost brilliance with girlish grace and is also an ideal companion for everyday wear since this popular stone looks wonderful worn with a pair of blue jeans.
Amethyst, morganite, and kunzite
Enjoy the tempting colours of fresh berries, cap- tured forever in precious stones. Lush purple is the distinctive colour of the amethyst, the most avidly sought stone of the quartz family. In classi- cal antiquity, amethysts were worn as amulets to protect their wearers against drunkenness. This is perhaps a reason why it is associated with the Shrovetide carnival month of February. The deli- cately pinkish, peach-coloured morganite belongs to the beryl family, while the equally attractive lilac-coloured kunzite is a member of the spo- dumene family. Like amethyst and morganite, kunzite’s special appeal originates in its lovely colour and high degree of transparency.
Reddish pink tourmalines
Each new gem seems more beautiful than the next! The finest nuances in colour are often decisive fac- tors determining whether a particular stone will be chosen by a discriminating client as her favourite gem. The rubellite is generally regarded as the most beautiful red variation of tourmaline. Whether viewed under natural or artificial light, its colour remains unchanged and constant. The tourmaline is inarguably gracious and beautiful, but it was prized for a very different reason by the Dutch, who discovered that rubbing these gems charges them with static electricity. Once charged, the stone will attract tiny particles. The Dutch put this attribute to good use: they used tourmalines to cleanse their tobacco pipes. And they accordingly gave this gem the rather unflattering name “aschentrekker.”
Classic fairytales used the obsolete word carbun- cle to describe all red gems, including the ruby. Not until many centuries later was this gem assigned to the corundum family. Together with the diamond and the emerald, the ruby ranks among the world’s most precious gemstones. Only one percent of all rubies are suitable for use in jewellery, and rubies that weigh more than three carats are extremely rare. This gem occurs in many different shades of red as confirmed by the eighteen different nuances of ruby red that ancient India was able to distinguish. Its particu- lar shade of red also indicates where the gemstone was mined: rubies the colour of pigeon’s blood frequently come from Burma, while reddish pur- ple rubies are chiefly found in Thailand.
The imperial topaz and the garnet
A lively and brilliant fire is one way to describe the gleam of the imperial topaz. A popular gem- stone among collectors, imperial topaz from Brazil is the costliest and rarest colour variety of topaz. Prized as the gem of monarchs, this stone is reputed to strengthen its wearer’s self- confidence. People who own garnets also have good reason to be self-confident. The name of this red gem derives from the Latin word granum, meaning grain. And indeed, most garnets occur in rounded crystalline shapes. The fiery orange- coloured mandarine garnet is an especially lumi- nous and rare variety.
Quartz is a family of minerals featuring identical chemical composition and similar physical prop- erties. A hardness of 7 on the Mohs scale guaran- tees that these stones’ beauty will last forever. The citrine’s charm originates in its warm golden yel- low hue, radiating cheerfulness and joy. Smoky quartz sparkles in a mysterious brown hue. And lemon quartz is distinguished by a rich yellow colour with a greenish cast. Artificially heating a yellowish quartz can create a pale green prasiolite, very rarely found in nature.