Valuation of Diamonds

All diamonds that De Beers brings on the market are classified beforehand into one of the 16,000 different standards of quality, according to form, quality, color and size. Besides London, there are such sorting centers in Lucerne in Switzerland, Gaborone in Botswana, Windhoek in Namibia, And Kimberley in South Africa.
Formerly, 20 percent of all diamonds were considered suitable for jewelry, having been of ''Gemstone quality.'' The rest were sold to the industry as so-called industrial diamonds to be used for drilling crowns, milling machines, cutting wheels,etc. Since 1983, another 20 percent have been classified as''almost gemstone quality'' and are cut mainly in India. The smallest diamonds and diamonds of lesser quality can be worked and offered to buyers other than the strictly controlled diamond market.
In the valuation of faceted diamond, color, clarity, cut, and carat are taken into consideration. These four c's decide the value of a diamond.





Grading for Color Diamonds are found in all colors. Mostly they are yellowish. In the grading, these are evaluated together with the purely colorless diamonds. The rarer strong colors (green, red, blue, and yellow), the so-called fancy color, are valued individually and fetch collector's prices. Brown and black diamonds also occur.
Formerly, terms and definitions in grading for color were not uniform and often confusing, until an international agreement was reached to cover the so-called "yellow series.'' This was publish in 1970 as RAL 560 A5E. Since then, various institute of America (GIA), the International Diamond Council (IDC), and the Confederation International de la Bijouterie, Joaillerie, Orfevreie des Diamants, Perles, et Pierres (CIBJO). Today, the IDC regulation, written in English,  are accepted worldwide. In the United State, the GIA system is most commonly used.
The old grading terms, the ''Old Terms,'' should not be used anymore. In fact, however, they are still in usage in the gemstone trade.
Experts use standard sample collections for consistent, comparison color grading.
Grading for Clarity In Germany only the inner perfection is understood as ''clarity,'' while in the United States and in Scandinavia aspects of the quality of the outer finish are taken into consideration. Enclosed minerals, cleavages, and growth lines affect clarity; they are collectively called inclusions, but formerly were called ''flaws'' or ''carbon spots.'' Polished diamond without any inclusion under a 10 x loupe are considered ''flawless.'' Inclusions visible with larger are not taken into account for grading.
Grading for Cut To grad for cut, the type and shape of cut, proportion, and symmetry as well as outer marks are taken into consideration. In Germany the normal cut is the ''fine brilliant cut'' in the rest of Europe the ''Scandinavian-standard brilliant.'' In the United States, the only widely used cut grading system is that of the American Gem Society, based on the ''AGS Ideal Cut.''

Diamond Imitation

The fact that the diamond can be confused, in appearance, with many gemstones can lead to fraud, although not in the legitimate retail trade. A colorless diamond looks similar to rock crystal, precious beryl, cerussite, sapphire, scheelite, sphalerite, topaz, and zircon. Also many yellowish stones can look like diamond to the eye of the layman.
A part from these, there are various synthetic stones that are used to imitate diamonds. Especially strontium titanate ( fabulite ), YAG, GGG (galliant), linobate, and cubic ziconia (CZ, djevalite) must be mentioned. A well known diamond imitation made from glass is the so-called strass.
In 1970 the first gem-quality diamonds were synthesized, but these still do not compete with natural diamonds. At first, they served only scientific purposes since they are too small to be worn as jewelry. In 2003, however, synthetic diamonds up to 2.5 ct appeared on the market. In the trade one also finds natural diamonds, colored artificially by various irradiation treatment.
Diamond-doublets are made with: upper part-diamond; lower part-synthetic colorless sapphire, rock crystal, or glass. Other doublets have synthetic spinel as upper part, and strontium titanate underneath.

Diamond

The name diamond refer to its hardness (Greek-adamas, the unconquerable). There is nothing comparable to it in hardness . Its cutting resistance is 140 times greater than that of ruby and sapphire, the gemstones next in hardness after diamond. However, the hardness of a diamond is different in the individual crystal direction . This allows one to cut diamond with diamond and/or with diamond powder. Because of the perfect cleavage, care must be taken not to accidentally bang against an edge of a diamond, and also when setting it. Its very strong luster sometime enables the experienced eye to differentiate between a diamond and its imitations. Diamond is generally insensitive to chemical reactions. High temperatures , on the other hand, can induce etchings on the facets. Therefore, special care must be taken during soldering.
In the last fifty years, it has been recognized that there are various types of diamonds with different characteristics. Science differentiates between type la, Ib, Ila, and IIb. This is of little importance to the trade, but does assist the cutter. Due to the optical effects, the high hardness, and its rarity, the diamond is considered the king of gemstones. It has been used for adornment since ancient times.

Value of Gemstones

There are no firm prices regarding gemstones. They are subject to fluctuations just as with other products. In the end, supply and demand regulate the gemstone market. In addition, economic purchasing power and fashion trends can heavily influence the demand for certain gemstones.  There are great differences in pricing and purchase between diamond and the other so-called colored gemstones.
Diamond Prices With diamonds, the consumer can compare prices easily. Value determining elements, such as color, purity, and cut, are internationally defined.and can be controlled. Of course, there are profit margins and pursuit of profit. One can, however, avoid outright fraud by dealing with diamond wholesalers and established jewelers . Here a code of honor prevails like nowhere else in world trade. On the diamond stock exchanges, the wholesale diamond markets, business has been sealed from even the earliest times with a firm handshake and a person's word.
Color stone prices With colored stones, price often fluctuates greatly, even in the serious trade, since gem extraction sometimes depends on chance happenings that cannot be predicted. As always, beauty, rarity, and gemstone size determine price. However, in contrast with diamond trade, there are no controlling organization, no possible exertion of influence on honest trade. Furthermore, many small businesses are active with extraction and production. They often seek direct contact with the consumer, particularly tourists who are in the buying mood, and deceitfully exploit their ignorance.
Price Lists Numerous institutions such as diamond stock exchanges, gemological facilities, and professional journals publish current market prices and long term price tendencies. This pricing information is intended for trade and traders and not for the consumer who incurs substantial surcharges set by traders.
Price of stones are usually expressed"per carat" .The carat price often progressively increases with the size of the stone. For example, a one carat piece might coast $750, but a two carat piece is not necessarily worth twice the amount, or @1500, but perhaps $3000 or more.
Less valuable stones such as agate are sold by grams and kilograms, not carat.

what is gem/gemstone?

There is no generally accept definition for the term gem or gemstone, but they all have something special, something beautiful about them. Most gemstones are minerals(e.g., diamond), mineral aggregates( such as lapis lazuli), or rocks ( such as onyx marble ). some are organic formations ( e.g., amber), and other gem materials are of synthetic origin( e.g., YAG ).
There is no definite demarcation.line , and woods, coal, bones, glass, and metals are all used for ornamentation. Some examples include jet ( a form of coal ), ivory ( tusks of elephants as well as teeth of other large animals), moldavite ( a glassy after-product of the striking of a meteorite), and gold nugget ( more or less large gold -lumps). Even fossils are sometimes used as ornamental material.
For some gemstone the source of specialness and beauty is the color, an unusual optical phenomenon, or the shine that makes them stand out in comparison to other stones. For other stones it is the hardness or an interesting inclusion that makes them special. Rarity also plays a role in the classification as gemstone.
Since the valued characteristics usually come into effect only through cutting and polishing, gemstones are also normally considered to be the cut stones. Cutting and polishing means refinement of what might be an other wise insignificant raw material.
There are several hundred distinct types of gems and gem materials. The number of the of the variations is about double that. From time to time, new gemstones are discovered or varieties with gemstone quality are found in minerals which have been already known.
Harder stones are suitable for jewelry, whereas softer stones are often sought after by amateur collectors as well as serious lapidaries.

Gemstones

Gems have intrigued humans for at least 10,000 years. The first known, used for making jewelry, include amethyst, rock crystal, ember, garnet, jade, jasper, coral, lapis lazuli, pearl, serpentine, emerald, and turquoise. These stones were reserved for the wealthy, and served as status symbols. Rulers sealed documents with their jewel-encrusted seals. Such treasures can now be admired at many museums and treasure-vaults.
Today, gems are worn not so much to demonstrate wealth, but rather jewelry is bought increasingly for pleasure, in appreciation of its beauty.
Certainly, also today, when purchasing a gemstone, a certain love for a special stone is part of it. Formerly, when people were less scientifically knowledgeable, gems always had an aura of mystery, something almost spiritual. That's why they were worn as amulets and talismans. Up to the present day, gemstones have sometimes been used as remedies against illness. They could be used in three different ways: the mere presence of the stone was sufficient to effect a cure; the gem was placed on the afflicted part of the body; or the stone was powdered and eaten.
Presently, medical science worldwide is experiencing a revival of the ideas of the Middle Ages in the use of precious stones through the doctrines of the Esoteric. As a  capital investment, however, of all gemstone really only diamonds are suitable. In fact, these have proven to hold on to their value, despite the travails of war or depression in the economy.
The truly modern problem is the imitation of gemstones that have become more and more sophisticated. Although replicas of precious matter have always existed, it is only in our modern times that imitating has turned into a booming economic sector with an often disreputable background.