GEMSTONES
This guide defines the five essential characteristics of gemstone quality. By understanding these characteristics, you'll be able to shop with confidence. Print this helpful list and take it with you shopping so you can make the best choice on a beautiful piece of gemstone.
CUT
Unlike diamonds, with gemstones you won't find an "ideal" cut geometrically configured for maximum brilliance. But a high-quality gemstone cut is one that displays the majority of the gemstone weight when set in jewelry, and presents the most even color, and exposes the fewest inclusions.
Cut plays a major role in determining the value of rubies and sapphires because it affects their color and clarity as well as their brilliance. For example, a stone that is cut too shallow can look pale and lifeless, and it can display flaws that would normally not be visible to the naked eye.
When choosing a sapphire or ruby, ensure that the gem doesn't display the bands of color common to corundum crystals, because if you can see these streaks, you can tell the gem was cut for maximum weight rather than beauty. Finally, when choosing an emerald, ensure none of the fissures and inclusions penetrates deeply into the gem, as it may cause the gem to break if subjected to a blow.
Cut plays a major role in determining the value of rubies and sapphires because it affects their color and clarity as well as their brilliance. For example, a stone that is cut too shallow can look pale and lifeless, and it can display flaws that would normally not be visible to the naked eye.
When choosing a sapphire or ruby, ensure that the gem doesn't display the bands of color common to corundum crystals, because if you can see these streaks, you can tell the gem was cut for maximum weight rather than beauty. Finally, when choosing an emerald, ensure none of the fissures and inclusions penetrates deeply into the gem, as it may cause the gem to break if subjected to a blow.
COLOUR
The jewelry industry recognizes the highest quality gemstones by their blue, green, or red hue, a medium to medium-dark tone, and saturated color. The best value is in colors that include "slight" traces of other colors, are not too light or dark, and have a lot of saturated color
Hue: Refers to a pure color such as (blue, red, green, orange). The most valuable gemstones are those that exhibit a pure color and only "slight" hues of other colors in addition to their primary color
Tone: Refers to the amount of color present. (Tone represents the depth of color, ranging from colorless to black). The lightest possible stone is colorless, the darkest is black. Tone is another word for lightness/darkness. Gemstone tone is described as "light," "medium-light," "medium," "medium-dark," and "dark." Saturation: Saturation or color purity describes the degree to which the hue is masked by brown or gray.
The most desirable gemstones, which show little gray or brown, are often described as having "vivid" or "strong" color saturation, Color purity described by GIA (Gemological institute of America): "Vivid," "strong," "moderately strong," "very slightly brownish or grayish," slightly brownish or grayish," "Brownish or grayish," (least pure)
CLARITY
When you try to find forms within stones or marks on their exterior, you are analyzing their clarity. Clarity is the degree to which a stone is free from external marks called blemishes and internal features called inclusions. " Flaw" is the term that is normally refers to both blemishes and inclusions.
Even though terms like "flaw" and "blemish" have negative connotation, their presence can be positive. Flaws are identifying marks that can help you identify your stone at any time.
They can lower the price of a stone without affecting its beauty. They can also increase the value of a stone by helping prove that it is from somewhere like Ceylon, Burma or Kashmir. (These places have a reputation for producing to - quality stones like sapphire, ruby). Flaws are especially important as evidence that your stone is natural. Jewelers and dealers are suspicious of flawless rubies and sapphires because that is usually a sign that the stone, is synthetic (man-made). Therefore instead of looking for a flawless stone, try to find one whose beauty and durability is not affected by its blemishes and inclusions.
The best value is found in gems that are lightly- to moderately included
Even though terms like "flaw" and "blemish" have negative connotation, their presence can be positive. Flaws are identifying marks that can help you identify your stone at any time.
They can lower the price of a stone without affecting its beauty. They can also increase the value of a stone by helping prove that it is from somewhere like Ceylon, Burma or Kashmir. (These places have a reputation for producing to - quality stones like sapphire, ruby). Flaws are especially important as evidence that your stone is natural. Jewelers and dealers are suspicious of flawless rubies and sapphires because that is usually a sign that the stone, is synthetic (man-made). Therefore instead of looking for a flawless stone, try to find one whose beauty and durability is not affected by its blemishes and inclusions.
The best value is found in gems that are lightly- to moderately included
The GIA divides colored stones into four clarity types:)
CARATThe term "carat" originated in ancient times when gemstones were weighed against the carob bean. Each bean weighed about one carat. In 1913, carat weight was standardized internationally and adapted to the metric system, with one carat equalling 1/5 of a gram. The wieght of small stones is frequently expressed in poin The carat weight of a gemstone is not necessarily an accurate gauge for gemstone size. |
CARAT WEIGHT (SIZE)
Different Densities: The carat weight of a gemstone does not necessarily allow you to accurately envision the size of the gemstone. Different gemstones have different densities (mass per unit volume), so two gems that appear to be the same size may actually have very different weights. For example, a ruby is denser than an emerald, so a 1-carat ruby will look smaller than a 1-carat emerald of the same dimensions
ENHANCEMENTS
Nearly all gemstones available have been enhanced. Those gemstones that have not been enhanced are very recognizable by the extravagant price they command. Some enhancements, such as heating and oiling, are an expected part of the polishing and finishing process and are accepted by the jewelry industry
Almost every ruby or sapphire you will find has been heated, which is a practice that has been going on for centuries. Heating completes a process nature started, enhancing the gemstone to amazing colors of blue and red. The centuries-old practice of immersing emeralds in oil (as cedar oil) has become so accepted that almost every emerald you will find has been oiled. The oil fills tiny fissures (common in emeralds) and makes them more beautiful.
The jewelry industry recognizes heating and oiling as acceptable and expected processes. Both of these processes are steps of the polishing and finishing process for almost all colored gemstones. The heating and oiling of gemstones are practices accepted by the jewelry industry, the American Gem Trade Association (AGTA).
Note: Heat treating is widely accepted because it causes a permanent improvement of the entire stone
Buyer's Tip
Nearly all gemstones available on the open market have been enhanced. Those that have not been enhanced command extravagant prices. Before buying a gemstone that has not been enhanced, ask to see the grading report from a well-known gemstone-grading lab
Disclosing Treatments
There is a great deal of controversy in the trade about the disclosure of gem treatments. Some feel that disclosure will confuse customers and hurt the colored-stone business. Others feel that disclosure is unimportant because treatments like dyeing, oiling, and heating have been practiced for centuries. Some describe treated gems as "faked" or "adulterated" and prefer t believe that the stones they sell are not treated when in fact they often are.
During the past ten years, however, the trade has become more aware of gem treatments and the trend now is towards full and voluntary disclosure of them to the public.
In spite of all this, consumers do have a right to know what they are buying, especially when they are spending large sums of money. In the USA, the Federal Trade Commission (FTC) advises that, if an enhancement treatment is not permanent Commission prohibits the sale of any gemstone (including diamond) that has been artificially colored by coating, irradiating or heating, or by nuclear bombardment unless the treatment is disclosed. In this context, the permanence of a treatment means that the gemstone must not revert to its original appearance under normal conditions of wear and display. A further concession to practicality allows for the non-disclosure of gem treatments, which are undetectable by a ' qualified gemological laboratory'.
During the past ten years, however, the trade has become more aware of gem treatments and the trend now is towards full and voluntary disclosure of them to the public.
In spite of all this, consumers do have a right to know what they are buying, especially when they are spending large sums of money. In the USA, the Federal Trade Commission (FTC) advises that, if an enhancement treatment is not permanent Commission prohibits the sale of any gemstone (including diamond) that has been artificially colored by coating, irradiating or heating, or by nuclear bombardment unless the treatment is disclosed. In this context, the permanence of a treatment means that the gemstone must not revert to its original appearance under normal conditions of wear and display. A further concession to practicality allows for the non-disclosure of gem treatments, which are undetectable by a ' qualified gemological laboratory'.
Care: Cleaning gemstone
After removing your gemstone jewelry, wipe it with a soft cloth to remove dirt and other residues.
The only cleaning method recommended for emeralds is the use of a soft cloth to gently rub off the accumulation around the gem and in the setting. Never use an ultrasonic cleaner or harsh cleanser to clean your emerald jewelry, as you may damage this soft and fragile gemstone.
For sapphires or rubies you can use either an ultrasonic cleaner, or a solution of one part ammonia and six parts water to clean your jewelry at home. If cleaning by hand, gentle scrubbing with a very soft brush should loosen most dirt and greatly increase the brilliance of the gemstone, but be careful not to scratch the metal of your setting.
The only cleaning method recommended for emeralds is the use of a soft cloth to gently rub off the accumulation around the gem and in the setting. Never use an ultrasonic cleaner or harsh cleanser to clean your emerald jewelry, as you may damage this soft and fragile gemstone.
For sapphires or rubies you can use either an ultrasonic cleaner, or a solution of one part ammonia and six parts water to clean your jewelry at home. If cleaning by hand, gentle scrubbing with a very soft brush should loosen most dirt and greatly increase the brilliance of the gemstone, but be careful not to scratch the metal of your setting.