Gemstones, Precious Metals & Diamonds Discovering The World Of Gemstones
Natural gemstones are found in nature. Laboratory-created stones, as the name implies, are made in a laboratory. These stones, which also are referred to as laboratory-grown, manufacturer-created, or synthetic, have essentially the same chemical, physical, optical, and visual properties as natural gemstones. Laboratory- created stones do not have the rarity or value of natural colored gemstones. By contrast, imitation stones look like natural stones in appearance only, and may be a manmade or natural stone. Laboratory-created and imitation stones should be clearly identified as such.

Gemstones may be measured by weight, size, or both. The basic unit for weighing gemstones is the carat, which is equal to one-fifth (1/5th) of a gram. Carats are divided into 100 units, called points. For example, a half-carat gemstone would weigh .50 carats or 50 points. When gemstones are measured by dimensions, the size is expressed in millimeters (for example, 7x5 millimeters).

Gemstone treatments or enhancements refer to the way some gems are treated to improve their appearance or durability, or even change their color. Many gemstones are treated in some way. The effects of some treatments may lessen or change over time and some treated stones may require special care. Some enhancements also affect the value of a stone, when measured against a comparable untreated stone. Treatments and/or enhancements should always be disclosed by the seller.

A WORD ABOUT PEARLS... Natural pearls are found in oysters and other mollusks. Cultured pearls also are grown in mollusks, but with human intervention; that is, an irritant introduced into the shells causes a pearl to grow. Imitation pearls are man-made with glass, plastic, or organic materials.

Because natural pearls are very rare, most pearls used in jewelry are either cultured or imitation pearls. Fine quality cultured pearls, because they are harvested from oysters or mollusks, are more expensive than imitation pearls. A cultured pearl's value is largely based on its size, usually stated in millimeters, and the quality of its nacre coating, which gives it luster. The pearls color, blemish, type, and shape are also considered.

ALL THAT GLITTERS... The word gold, used by itself, means all gold or 24 karat (24K) gold. Because 24K gold is soft, it's usually mixed with other metals to increase its hardness and durability. If a piece of jewelry is not 24 karat gold, the karat quality should accompany any claim that the item is gold.

The karat quality marking tells you what proportion of gold is mixed with the other metals. Fourteen-karat (14K) jewelry contains 14 parts of gold, mixed in throughout with 10 parts of an alloy metal. The higher the karat rating, the higher the proportion of gold in the piece of jewelry.

Most jewelry is marked with its karat quality, although marking is not required by law. Near the karat quality mark, you should see the name or the U.S. registered trademark of the company that will stand behind the mark. The trademark may be in the form of a name, symbol or initials. If you don't see a trademark accompanying a quality mark on a piece of jewelry, look for another piece.

Platinum is a precious metal that costs more than gold. It usually is mixed with other similar metals, known as the platinum group metals: iridium, palladium, ruthenium, rhodium and osmium.

Different markings are used on platinum jewelry as compared with gold jewelry, based on the amount of pure platinum in the piece. The quality markings for platinum are based on parts per thousand. For example, the marking 900 Platinum means that 900 parts out of 1000 are pure platinum, or in other words, the item is 90% platinum and 10% other metals. The abbreviations for platinum - Plat. or Pt. - also can be used in marking jewelry.

The words silver or sterling silver describe a product that contains 92.5% silver. Silver products sometimes may be marked 925 which means that 925 parts per thousand are pure silver. Some jewelry may be described as silverplate: a layer of silver is bonded to a base metal. The mark coin silver is used for compounds that contain 90% silver. According to the law, quality-marked silver also must bear the name or a U.S. registered trademark of the company or person that will stand behind the mark.

TAKING THE GUESSWORK OUT OF DIAMOND BUYING... Most people know little about diamonds. That's why the American Gem Society came into existence over 70 years ago. Thanks to Society members, we now have precise standards for evaluating diamonds, commonly known as the 4 Cs: Cut, Color, Clarity, and Carat Weight. The American Gem Society Diamond Grading Standards evaluate three of the four value factors — cut, color, and clarity — on its own 0 –10 scale. 0 (Zero) is the highest grade, and 10 is the lowest. AGS "0" indicates an AGS Ideal Cut diamond that has no color and no inclusions or internal characteristics. The three factors are expressed separately along with the fourth factor, the carat weight of the gemstone, for the final American Gem Society Grade.

THE SCIENCE OF DIAMONDS... While not everyone will share the same opinion as to what constitutes beauty, most people want a diamond that expresses their individual taste and personality. Here's what you should consider first, however, before buying a diamond: Cut. Of all the 4 Cs, cut has the greatest effect on a diamond's beauty. In grading, cut evaluates the cutters skill in the fashioning of the diamond.

Diamonds have a unique ability to manipulate light efficiently. This unique ability can be released and maximized only by cutting and polishing the diamond to an extremely high level of accuracy. The American Gem Society Cut Grading System considers not only the proportions of a diamond, but also the craftsmanship of its overall symmetry and polish. It is unique in that it uses the latest in technology to analyze the cut's impact on the diamond's light performance.

Color. A truly colorless diamond is extremely rare. Most diamonds possess varying degrees of yellow or brown and small, subtle differences in color can make a substantial difference in value. If a diamond is well cut, the diamond's refraction and dispersion often will disguise certain degrees of coloration. Unless a diamond is a fancy color (or any color other than colorless to light yellow or brown), the American Gem Society Color Grading System places it on a 0 to 10 scale, 0 being colorless. To accurately and consistently grade color, an American Gem Society experienced grader will utilize special lighting to compare the diamond being graded to a set of American Gem Society Master Color Comparison Diamonds, which have met exacting standards of cut, color, clarity, and carat weight.

Clarity. Clarity is the evaluation of a diamond's internal and external characteristics. The fewer inclusions or blemishes, the more desirable the diamond. Inclusions are internal, that is, inside the diamond. Crystals are merely minerals trapped inside the diamond; feathers are breaks in the diamond. Blemishes are usually very small and are only on the surface of diamonds. To locate these tiny characteristics, an American Gem Society member jeweler will use a binocular microscope that magnifies the diamond ten times. Then, evaluating the size, location, nature, number, and color of all the inclusions and blemishes, a clarity grade from 0-10 is assigned – 0 being flawless or internally flawless.

Carat. The standard used to measure diamond weight is the carat. A carat equals 1/5 of a gram (or 1/142 of an ounce). Each carat is further divided into points, each point representing 1/100th of a carat. While weight may be the least important of the four Cs in determining value, it may be the easiest of the four Cs to gauge accurately and is the most objective. As diamonds increase in size, their cost tends to increase geometrically. Thus, a one-carat diamond may cost more than twice as much as a one-half carat stone of equal quality. Also, as previously stated, weight does not always enhance the value of a diamond. In fact, when a diamond is improperly cut, added weight may serve only to reduce its brilliance. For these reasons, you should consult with an American Gem Society titleholder regarding the question of carat weight. Courtesy of American Gem Society