4C

Treasure of Time
Every diamond is unique. Each reflects the story of its arduous journey from deep inside the earth to a cherished object of adornment. Yet all diamonds share certain features that allow us to compare and evaluate them. These features are called the 4Cs.

How GIA Grades Your Diamond
GIA has been entrusted with grading some of the world’s most famous diamonds, and brings the same unmatched expertise to grading yours.
Independent and nonprofit, GIA is considered the final word on a diamond’s authenticity and quality. GIA developed the 4Cs and the International Diamond Grading System™, the standard used around the globe.
GIA screens every gemstone to identify synthetics, simulants and known treatments. Expert gemologists examine each diamond under controlled lighting and viewing conditions, in order to provide the most rigorous assessments of a diamond’s 4Cs.
Every GIA grading report contains these assessments along with additional descriptive information and state-ofthe-art security features.
Buying a diamond is a momentous decision. GIA reports let you make it with confidence.
Learn more at www.gia.edu

Wonder of Nature
There is no other gemstone quite like a diamond. It is found in the most remote places on earth, and the fact that it forms at all is something of a miracle. It takes about one ton of rock to recover less than half a carat of rough, making diamond one of the rarest and most desired gemstones in the world. A diamond is a testament of endurance and strength – and not surprisingly, the ultimate symbol of love.

CARAT

One carat equals 200 milligrams in weight.
For diamonds under one carat, each carat is divided into 100 points – similar to pennies in a dollar. 0.75 ct. = 75 points, 1/2 ct. = 50 points.

COLOR

GIA COLOR SCALE

The GIA Color Scale extends from D (colorless) to Z (light yellow or brown).
Although many people think of gem quality diamonds as colorless, truly colorless diamonds are actually very rare. Most diamonds used in jewelry are nearly colorless with tints of yellow or brown.

Color grades are determined by comparing each diamond to a master set. Each letter grade represents a range of color and is a measure of how noticeable a color is.

Fluorescence Some diamonds can emit a visible light when exposed to ultraviolet radiation, but fluorescence is not a factor in determining color or clarity grades. However, a description of its strength and color is provided on GIA Reports as an additional identifying characteristic.

CLARITY

GIA CLARITY SCALE

The GIA Clarity Scale includes eleven clarity grades ranging from Flawless to I3.
Because diamonds form under tremendous heat and pressure, it is extremely rare to find a diamond that lacks any internal and external characteristics. These characteristics are a by-product of its formation and help gemologists separate natural diamonds from synthetics and simulants, and identify individual stones.

Sample Clarity Diagrams

CUT

GIA CUT SCALE

The GIA Cut Scale ranges from Excellent to Poor.
A polished diamond’s beauty lies in its complex relationship with light. The magnificent display you see is made up of three attributes: Brightness is the combination of all white light reflecting from the surface and interior of a diamond. Fire describes the “flares” of color emitted from a diamond. Scintillation describes the pattern of light and dark areas and the sparkle you see when the diamond, the light, or the observer moves.
A diamond’s proportions affect its light performance, which in turn affects its beauty and overall appeal. Diamonds with fine proportions, symmetry, and polish optimize their interaction with light, and have increased brightness, fire, and scintillation.
GIA assesses these factors for standard round brilliant diamonds in the D-to-Z color range.

Anatomy of a Diamond

Beauty and Its Beholder

The 4Cs provide a way to objectively compare and evaluate diamonds, but numbers alone can’t describe a diamond’s mysterious and captivating beauty – for that, you’ll have to visit your local jeweler to see one for yourself.

Fancy Color Diamonds

Diamonds in the normal color range are colorless through light yellow and are described using the industry’s D-to-Z color-grading scale. Fancy color diamonds, on the other hand, are yellow and brown diamonds that exhibit color beyond the Z range, or diamonds that exhibit any other color face-up. These rare specimens come in every color of the spectrum, including, most importantly, blue, green, pink, and red.

Gem diamonds in the D-to-Z range usually decrease in value as the color becomes more obvious. Just the opposite happens with fancy color diamonds: Their value generally increases with the strength and purity of the color. Large, vivid fancy color diamonds are extremely rare and very valuable. However, many fancy diamond colors are muted rather than pure and strong.

Fancy color diamonds come in almost any color you can imagine. Red, green, purple, and orange are generally the most rare, followed by pink and blue. Yellows and browns are the most common fancy colors, but they’re generally less valuable than the rarer colors.

Blacks, grays, and fancy whites are considered fancies, too. Some have been fashioned into gems. The 67.50-carat Black Orloff diamond, named after the Russian Princess Nadia Vyegin-Orloff, is the most well-known example.

Spectacular prices in high-profile auctions are another factor in the increased awareness of fancy color diamonds. Not all fancy color diamonds command such high prices, however. Many people consider yellow and brown fancies less desirable than near-colorless stones of equal weight and clarity. And deeper yellows and browns are generally less valuable than other fancy colors.

Fluorescence

Fluorescence is the visible light some gemstones emit when they are exposed to invisible ultraviolet (UV) rays. In natural diamonds, blue is the most common color of fluorescence, but other colors may be visible.

On a GIA Diamond Grading Report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV, which is an essential component of daylight. To learn more about diamond fluorescence, download this PDF.

Emerald

Emerald has many special qualities, but colored stone professionals generally agree that emeralds are, most of all, about color. Emerald has been the standard for green among colored stones for thousands of years.

As with other colored stones, it requires a well-trained eye to recognize the sometimes subtle variations that make significant differences in emerald value. This is especially true in the higher qualities.

Color

The most desirable emerald colors are bluish green to pure green, with vivid color saturation and tone that’s not too dark. The most-prized emeralds are highly transparent. Their color is evenly distributed, with no eye-visible color zoning. If the hue is too yellowish or too bluish, the stone is not emerald, but a different variety of beryl, and its value drops accordingly.

The intensity of the green in the finest emeralds might not be equaled by anything else in nature.

Chromium, vanadium, and iron are the trace elements that cause emerald’s color. The presence or absence of each and their relative amounts determine the exact color of an emerald crystal.

Emerald appearance is sometimes associated with its mine location. Colombian emeralds are said to have a warmer and more intense pure green color. Zambian emeralds are said to have a cooler, more bluish green color. In spite of these theories, the truth is that emerald appearance overlaps between sources.

Clarity

Emeralds typically contain inclusions that are visible to the unaided eye. Because of this, trade members and some consumers understand and accept the presence of inclusions in emeralds. Eye-clean emeralds are especially valuable because they’re so rare.

Emerald inclusions are often described as looking mossy or garden-like. They’re sometimes called “jardin,” which is French for garden.

In colored stones, transparency and clarity are closely linked. This is especially true for emeralds. The trade generally accepts eye-visible inclusions in higher-quality emeralds. But when the inclusions have a negative effect on transparency and clarity, they also dramatically reduce value.

In early 2000, the GIA Laboratory began offering a classification service for emerald clarity treatments. The laboratory examines a loose stone and provides an Emerald Report that includes a digitally generated color image of the stone taken at the time it’s examined. The report describes the level of clarity enhancement as minor, moderate, or significant. The GIA Laboratory emphasizes that it uses the classification system only to evaluate the level of treatment, and not to offer an overall clarity grade for the stone.

Cut

The cutter must consider the rough’s depth of color, durability, and inclusions when making cutting decisions. Mistakes cause weight loss, which greatly reduces the value of a potentially valuable gem.

Four characteristics of emerald crystals make them difficult to cut. First, almost all emeralds have significant fractures (sometimes called fissures in the trade). A cutter must design the cut to minimize the effect of those fractures on the finished stone.

The second factor is due partly to those inherent fractures: Emeralds are more brittle than a gem like corundum. This makes them vulnerable to damage during cutting, polishing, and setting, or even during careless daily wear. The emerald cut can help protect against damage because the vulnerable corners are faceted and provide a comparatively safe place for prongs.

Third, because color is so important in establishing an emerald’s value, the cut must maximize the effect of hue, tone, and saturation. The cutter can affect color by adjusting an emerald’s proportions and number of facets. The cutter can darken a pale stone with a deep cut, a small table, and fewer facets, or lighten a dark stone with a shallow cut, a large table, and additional facets.

Fourth, the bluish green to yellowish green dichroism of many emerald crystals encourages the cutter to orient the table so it’s perpendicular to the crystal’s length. That way, the more apparent color in the cut gem is the bluish green that so many emerald lovers prize.

Colombian rough is especially challenging due to the distribution of coloring agents during formation. Its color is more intense closer to the surface. Without careful planning and cutting, the finished stone might be much lighter in color than the original material.

Carat Weight

Fashioned emeralds come in a wide range of sizes. There are emeralds in museums and private collections that weigh hundreds of carats. At the other extreme are tiny emeralds that weigh fractions of a carat.

The Sandawana emerald mine in Zimbabwe is known for its tiny, yet vividly colored stones. Its emeralds are as small as 1 mm square, but they’re still intensely green. The mine’s cut stones average about 0.05 to 0.25 carat, and rarely weigh more than 1.50 carats. Popular jewelry sizes are usually somewhere in between.

The smallest sizes range from 1 mm to 5 mm, with weights from 0.02 to 0.50 carat, while 1 to 5 carat stones are popular as center stones. Prestigious pieces of jewelry can include emeralds that weigh over 20 carats.

Quality-for-quality, the price of emerald can rise dramatically as the size increases.

Sapphire

Sapphire is one of the Big 3 of jewelry colored gemstones—the other two are ruby and emerald. A durable stone that’s designated as a birthstone for September, it captures jewelry buyers with its practicality and aura of romance.

Color

Sapphires come in a wide range of colors, and each color has its own quality variations. In general, the more intense the color and the fewer the distracting zones of unattractive color, the more valuable the stone.

Color has the most important influence on blue sapphire’s value. The most highly valued blue sapphires are velvety blue to violetish blue, in medium to medium dark tones. Preferred sapphires also have strong to vivid color saturation. The saturation should be as strong as possible without darkening the color and compromising brightness. Sapphires with these qualities command the highest prices per carat.

At the other end of the price scale are commercial-grade sapphires with greenish blue color or strong greenish blue pleochroism. Pleochroism is different colors seen in different crystal directions. Less valuable blue sapphires might be grayish, too light, or too dark.

The major fancy sapphire color categories are padparadscha, pink and purple, orange and yellow, green, and colorless and black. Each category has its own color range, causes of color, and market.

The fancy sapphires that people in the trade call padparadscha are very beautiful. They typically have a high per-carat value, too—much higher than other types of fancy sapphires.

Their color can be hard to describe. Some people say padparadscha sapphire colors should be called salmon or sunset. Others compare the color to the flesh of a ripe guava.

In spite of these differing color descriptions, people in the industry usually agree that padparadscha sapphire colors are intensely saturated and range from light to medium pinkish orange to orange-pink.

Pink sapphires range from red to purple with weak to vivid color saturation and lighter tone. Purple sapphires are similar in color but darker and always have purple as the dominant color. They range from medium to dark reddish purple to violetish purple with weak to vivid color saturation.

Corundum appears in an array of yellow and orange hues that includes bright lemon, soft peach, and vivid tangerine.

In specific color terms, yellow sapphires range from light to dark greenish yellow to orangy yellow with weak to intense color saturation. The finest yellow sapphire is yellow to orangy yellow with vivid saturation.

Orange sapphires range from yellowish orange to reddish orange. The finest orange sapphires are strong, pure orange to red-orange with medium tone and vivid saturation.

Green sapphires range from light to dark bluish green through yellowish green, and are usually low in saturation. Green sapphire is readily available, but its color isn’t very marketable. Its color is sometimes described as khaki or olive. That’s because the stones tend to have low saturation or unattractive color zoning.

People in the trade refer to corundum in its purest form as either colorless sapphire or white sapphire. The closer corundum comes to having no color, the more valuable it is as a colorless sapphire. Traces of extremely light gray, yellow, brown, and blue are common, and reduce the value. Colorless sapphires have been popular as small accent stones in jewelry.

Color-change sapphires are corundum’s chameleons—stones that change color under different lighting. Under daylight equivalent (fluorescent) light, the typical color-change sapphire’s basic color ranges from blue to violet. Under incandescent light, it ranges from violetish purple to strongly reddish purple. Some rare color-change sapphires change from green in daylight to reddish brown in incandescent light.

When gem experts judge color-change sapphires, they describe the color change as weak, moderate, or strong. The strength of the stone’s color change is the most important quality factor affecting its value, followed in importance by the actual colors of the stone.

As with all colored stones, the color of star corundum has a great effect on its value. The best star corundum has a crisp, distinct star against strongly saturated color. If the color is too light, it doesn’t provide enough contrast for the star’s rays, and the star will be less visible.

Star corundum can be red, blue, black, gray, purple, or yellow—practically every color under the sun. The term “star sapphire” encompasses all colors of star corundum except red, which is called star ruby.

Naturally, some colors of star corundum are valued more highly than others. In general, the most prized colors are the same as the colors most valued in non-phenomenal corundum: red and blue.

Trade terms based on sources can represent certain colors and qualities that are associated with a stone’s source. The qualities might be typical of that source or they might represent the finest stones from that source. But a single source never consistently yields gems that are all the same color and quality. In fact, the descriptive term might represent only a small percentage of stones from that source. The appearance of stones from a particular source often varies over time, and the original quality associated with that source might no longer match the material produced.

New sources can produce material very similar to that from classical sources or with a slightly different, but just as beautiful, appearance.

Clarity

Blue sapphires typically have some inclusions, but they generally have better clarity than rubies. Blue sapphires with extremely high clarity are rare, and very valuable.

Several types of inclusions are found in sapphires. Among these are long thin mineral inclusions called needles. Fine needles are called silk when they occur as the mineral rutile in intersecting groups. Other clarity characteristics in sapphire are included mineral crystals, partially healed breaks that look like fingerprints, color zoning, and color banding.

Generally, inclusions make a stone less valuable. Price can drop substantially if the inclusions threaten the stone’s durability. Even so, inclusions can actually increase the value of some sapphires. Many of the most valuable Kashmir sapphires contain tiny inclusions that give them a velvety appearance. They scatter light, causing the coveted visual effect without negatively affecting the gem’s transparency.

Star rubies and star sapphires belong to the phenomenal corundum category. The star effect is called asterism. It’s caused by reflections from tiny, needle-like inclusions that are oriented in several specific directions. Stars are usually made up of 2, 3, or 6 intersecting bands, resulting in 4, 6, or 12 rays.

The most common stars have 6 rays, and 12-rayed stars are quite rare. Two different sets of inclusions—one of rutile and one of hematite—oriented in slightly different directions can cause a 12-rayed star.

Hematite inclusions cause asterism in black star sapphires. The sapphire’s color is actually yellow, green, or blue, but the inclusions make it appear dark brown or black.

The finest star is distinct, centered on the top of the stone, and visible from a reasonable distance, about arm’s length. The star’s quality should be the same when viewed from all directions.

The rays should be uniform in strength, reach from one side to the other, and intersect at the top of the stone. They should be straight, not fuzzy, wavy, or broken, and they should contrast strongly against the background color. The star should also have elegant “movement.” This means that, as you rock the stone, the star should move smoothly across the surface with no dead spots.

The best and most expensive star corundum is semi-transparent, with just enough silk to create a well-defined star. Too much silk can harm transparency and also lead to poor color, lowering the value of the stone considerably.

Cut

The shape of a rough sapphire crystal influences the finished stone’s shape and size. Rough sapphire’s most common crystal form is a barrel- or spindle-shaped hexagonal pyramid. For this reason, finished sapphires are often deep.

To achieve the best overall color, maintain the best proportions, and retain the most weight possible, cutters focus on factors like color zoning, pleochroism, and the lightness or darkness of a stone.

Color zoning—areas of different colors in a stone—is a common sapphire characteristic. Blue sapphire often has angular zones of blue and lighter blue. To accommodate color zoning in some sapphires, cutters orient the concentrated color in a location that offers the best visible color in the cut stone.

In Sri Lankan sapphires, the color is often concentrated close to the surface of the crystal. If a cutter can orient the culet within the concentrated area of color, the stone will appear entirely blue in the face-up position.

Pleochroism is different colors in different crystal directions. Blue sapphires often have greenish blue and violetish blue pleochroism. It’s most desirable to orient the cut so the stone shows the violetish blue color when it is set in jewelry.

Star corundum must be cut as a cabochon to display asterism. A finished stone’s attractiveness depends on the star’s orientation and the cabochon’s symmetry, proportions, and finish.

The cabochon must have an appealing appearance, with the star properly centered when the gem rests on its base. The stone’s outline should be symmetrical.

For most stones, the dome should be fairly high—about two-thirds of the stone’s width—to focus the star sharply. If it’s too high, the phenomenon loses its graceful motion when the stone is tilted. Excessive height also makes the stone difficult to mount.

If the dome is cut too shallow, the star will be visible only from directly above. Black star sapphires, however, are prone to parallel breaks, so they’re usually cut very flat to reduce the risk of damage.

A stone should not have excess weight below the girdle that doesn’t contribute to the optical effect or reinforce color.

Carat Weight

Blue sapphires can range in size anywhere from a few points to hundreds of carats, and large blue sapphires are more readily available than large rubies. However, most commercial-quality blue sapphires weigh less than 5.00 carats.

Large commercial-quality blue sapphires are more common than large fine-quality ones. As a result, size makes more of a difference in the price of fine-quality sapphire. A fine-quality 5.00 carat blue sapphire sells for approximately five times more per carat than the same-quality 1.00 carat stone.

A commercial-quality 5.00 carat stone sells for only about twice as much per carat as a 1.00 carat blue sapphire of the same quality.

These examples are not meant to be exact pricing guidelines, but to illustrate how much the per-carat price can go up as the size and the quality rise.

Ruby

Ruby can command the highest prices of any colored gemstone. The per-carat prices of fine-quality rubies have been rising consistently, many times breaking auction records.

For better-quality material, slight differences in color can make significant differences in value. For top-color ruby that’s also free of eye-visible inclusions, the price rises even more.

The per-carat price of ruby can also increase dramatically as size increases, especially for better-quality stones.

Color

Color is the most significant factor affecting a ruby’s value. The finest ruby has a pure, vibrant red to slightly purplish red color. As the color becomes too orangy or more purplish, the ruby moves down the quality scale. The highest-quality rubies have vivid color saturation.

The color must be neither too dark nor too light to be considered finest quality. If the color is too dark it has a negative effect on the stone’s brightness. At the other extreme, if the color is too light, the stone is considered pink sapphire, even if color strength or intensity is high.

Some gem dealers debate the borderline between ruby and pink sapphire. Historically, the word ruby referred to shades of red, which technically included pink. There are also cultural differences in the interpretation of ruby versus pink sapphire. In some gem-producing nations such as Sri Lanka, pink colors were always considered ruby, while in many consuming countries it is classified as pink sapphire.

The GIA Laboratory uses a controlled set of comparison stones called masterstones to determine if corundum is ruby or if it’s pink, purple, or orange sapphire. The laboratory grades its masterstones on the principle that red must be the dominant hue before a stone can be called a ruby. In the gem trade, though, identification of the dominant hue is subject to personal perception.

Blood is another symbol of ruby’s color. Descriptions have compared ruby to the “blood from the right ventricle” or the first two drops of blood from a freshly killed pigeon. Historically, the term “pigeon’s blood” described the red to slightly purplish or pinkish red color of rubies with a soft, glowing, red fluorescence.

Traditional descriptions like these are useful for evoking images and describing color among professionals. But they can be subject to misinterpretation when used to describe a ruby’s actual color.

Trade terms can represent certain colors and qualities that are associated with a stone’s source. The qualities might be typical of that source or they might represent the finest stones from that source.

But a single source never consistently yields gems that are all the same color and quality. In fact, the descriptive term might represent only a small percentage of stones from that source. The appearance of stones from a particular source often varies over time, and the original quality associated with that source might no longer match the material produced.

New sources can produce material very similar to rubies from classical sources or with a slightly different appearance, but just as beautiful.

Clarity

People in the trade expect rubies to have at least some inclusions because inclusion-free rubies are practically nonexistent. Ruby value depends on how visible the inclusions are. Obvious inclusions or inclusions that reduce transparency or brightness lower a ruby’s value dramatically.

If large and prominent inclusions are located under the table facet, they greatly diminish the transparency, brilliance, and value of the stone. Inclusions can also limit a ruby’s durability. Significant surface-reaching fractures can pose durability threats.

Typical ruby clarity characteristics include thin mineral inclusions called needles. When the mineral is rutile and needles are present in intersecting groups, it is called silk. Needles might be short or long and slender, and they might appear to be woven tightly together.

Ruby can also contain needles composed of other minerals, small crystals, zones of color variation, or inclusions that resemble fingerprints.

Some inclusions can actually contribute positively to a gem’s appearance. The presence of rutile silk causes light to scatter across facets that might otherwise be too dark. This adds softness to the color and spreads the color more evenly across the ruby’s crown.

Needles that intersect can also cause the star effect, called asterism, when the stone is cut with a curved upper surface.

Cut

Several factors affect the cut and proportion of rubies on the market. A ruby’s crystal shape dictates its suitability for certain cuts. The most common shape is a flat tabular hexagonal shape, but ruby crystals from some sources can be elongated.

To accommodate these crystal shapes, the most common shapes of fashioned rubies are ovals and cushions, with brilliant-cut crowns of kite-shaped and triangular facets, and step-cut pavilions with concentric rows of rectangular or square facets.

Round, triangular, emerald-cut, pear, and marquise rubies are also available. But these shapes are rare in larger sizes and higher qualities.

Ruby rough is very expensive, so cutters try to conserve as much weight as possible. They might fashion flattened ruby rough into shallow stones, even though light escapes through flattened pavilions, causing an unattractive see-through area in the stone called a window.

Pleochroism—the appearance of different colors in different crystal directions—is another factor that influences cut. In ruby it typically appears as red to purplish red in one crystal direction and orangy red in the other. Cutters can minimize the orangy red color by orienting the table facet perpendicular to the long crystal direction. Even so, it’s not always possible to orient a ruby for ideal color return because the potential loss of weight would be too great.

Size and Weight

Fine-quality rubies over one carat are very rare, but commercial-quality rubies are commonly available in a wide range of sizes. The price per carat goes up significantly for ruby as it increases in size.

For example: A commercial-quality 5-carat ruby might sell for about twice as much per carat (10 times total stone value) as a commercial-quality 1-carat ruby, while a fine-quality 5-carat ruby sells for over five times more per carat (25 times total stone value) than a fine-quality 1-carat ruby.

These examples are not meant for exact pricing guidelines, but to illustrate how much the per-carat price can go up as the size and the quality rise.

Diamond Reports

Grading Diamond Color

Since light source and background can have a significant impact on a diamond's appearance, diamond color is graded in a standardized viewing environment against color masters. A minimum of two color graders enter their independent evaluations into the system and depending on the agreement of these grades, and the weight and quality of the diamond, it may be sent to additional graders who enter their own color opinions. The grade is not determined until there is sufficient consensus.

Grading Diamond Clarity

Diamond clarity is graded under standard viewing conditions with 10x magnification. The preliminary grader carefully examines the diamond in order to identify clarity/finish characteristics and evidence of any clarity treatments such as fracture filling or laser drilling.

A minimum of two graders assigns their impression of the diamond's clarity, polish, and symmetry. Next they plot the clarity characteristics on the diagram most representative of the diamond's shape and faceting style.

Grading Diamond Cut

GIA provides a diamond cut quality grade for standard round brilliant diamonds that fall into the D-to-Z color range. To develop their Cut Grading System, GIA performed extensive computer modeling of round brilliant diamonds over a 15-year period and conducted more than 70,000 observations on actual stones to validate the research. This system can now predict the cut grade for more than 38.5 million proportion sets.

GIA's Excellent to Poor Cut Diamond Grading System assesses the diamond's overall face-up appearance to predict the intensity levels of brightness, fire, and scintillation (the diamond's sparkle and interplay with light). GIA also screens every diamond submitted to determine if it is synthetic.

Diamond Carat Weight Measurement

To determine diamond carat weight, the diamond is weighed using an extremely accurate electronic micro-balance that captures the weight to the precise fifth decimal place (the nearest ten-thousandth of a carat). An optical measuring device is used to determine the diamond's proportions, measurements, and facet angles.

Other Gemstone Reports

Grading Fancy-Color Diamonds

While the vast majority of diamonds fall in the D-to-Z color range, nature occasionally produces diamonds with a naturally occurring blue, brown, pink, deep yellow or even green hue. The geological conditions required to yield these colors are rare, making diamonds with distinct and naturally occurring shades scarce and highly prized.

Unlike colorless and near-colorless diamonds, fancy-color diamonds are evaluated less for brilliance or fire and more for color intensity. Shades that are deep and distinct are rated higher than weak or pale shades.

GIA describes color in terms of hue, tone and saturation. Hue refers to the diamond''s characteristic color, tone refers to the color''s relative lightness or darkness and saturation refers the color''s depth or strength. Using highly controlled viewing conditions and color comparators, a fancy color grader selects one of 27 hues, then describes tone and saturation with terms such as "Fancy Light," "Fancy Intense," and "Fancy Vivid." The color system GIA developed is used worldwide.

GIA offers two types of grading report for colored diamonds. The GIA Colored Diamond Grading Report contains the same comprehensive diamond 4Cs information as the GIA Diamond Grading Report, while the GIA Colored Diamond Identification and Origin Report (also known as the color-only report) is limited to color grade and the origin of the color (natural or treated).

Pearl Classification and Grading

For more than 100 years, discoveries in pearl culturing have revolutionized the market and essentially replaced natural pearls in jewelry.

A natural pearl occurs when an irritant, such as a parasite, works its way into a particular species of oyster, mussel or clam. In defense, the mollusk secretes fluid, called nacre, to coat the irritation. Over time, layers of nacre form natural pearl. In cultured pearls, the irritant is a surgically implanted bead or bit of shell.

The ability to consistently generate what was once a rare phenomenon has created a much wider audience for the appreciation and purchase of pearls. But it has also led to confusion about levels of quality and how to determine them. Cultured pearls are produced in a wide variety of colors, shapes, and sizes and grading has become proportionately complex.

In response, GIA has created a standard for describing pearl quality just as it did with diamonds. GIA''s system, launched in 1998, is based on 7 Pearl Value Factors™: size, shape, color, luster, surface quality, nacre quality, and matching.

Colored Gemstone Identification

While renowned for its diamond grading expertise, GIA also receives a vast array of colored gemstones for identification. Over the decades, the Institute has created a database of information on more than 100,000 individual colored gemstones. Using this database and sophisticated analytical tools, GIA graders and researchers can pinpoint a gem''s identity and, depending on the gemstone, its geographic origin. They also identify synthetics, simulants, and stones that have undergone treatment. A particularly important activity is determining whether a gemstone''s color is natural or the result of a treatment process.

GIA''s processes for evaluating colored stones involve multiple graders and the same item identification and tracking procedures used in diamond grading.

Ring Size

Here are some helpful tips for choosing a ring size by measuring your finger.

• Measure your finger at the end of the day.
• Do not measure your finger when your finger is too warm or cool.
• Remember that left and right hands differ slightly in size. A ring worn on a left finger will not be a perfect fit for a finger on the right hand.
• Make sure that the chosen size leaves enough room for the ring to pass easily along the entire length of the finger.
• You may use a tape measure for finding the circumference of your finger in millimetres. This measurement corresponds to the size of the ring.
• If you are not certain of a size choose the larger size or add a half size. Please note that the style of the ring will also affect the choice of size: a large ring is made to be worn more loosely than a smaller one.

Jewelry Care

Jewelry is one of our most intimate and cherished accessories. An elegant pair of pearl and platinum earrings, for example, makes an individual statement, nestled against the skin and resplendent in lustrous light. Yet, according to experts at the nonprofit GIA, chemicals found in everyday substances like hairspray, lotions, perfumes, or other cosmetics can permanently damage the nacre of your dazzling pearl and corrode the alloys in that shiny setting.

Understanding how to care for your treasured jewelry can make a world of difference in maintaining its beauty and keeping its heirloom quality sparkling for generations to come. GIA says light and heat can affect a colored gemstone’s durability and color. Just as the sun’s harmful rays can damage our skin, over time and in excess, it can also fade and weaken some gemstones, such as amethyst, kunzite, topaz, and pink conch-shell cameos. Pearls and other delicate materials, like ivory, will bleach under extreme exposure to light. Other gems, especially amber, can darken over time when exposed to too much light.

Excessive heat and sudden temperature changes may also fracture the gem. Heat can easily remove the natural moisture some gems need to keep their beauty. Pearls, for instance, can dry out, crack and discolor. Opals will turn white or brown, develop tiny cracks, and might lose their play-of-color.

Exposure to chemicals can damage and discolor precious metals – gold, silver, and platinum – and may harm some colored gems. Fine jewelry should be removed before diving into a chlorinated swimming pool, or before using household cleaners. Many of these cleaners contain ammonia, and are only safe for diamonds and the more durable colored gems. Chlorine bleach, another common household solvent, can pit gold alloys.

GIA recommends cleaning most colored gems with warm water, mild soap (no detergents), and a soft brush. A pulsed-water dental cleaning appliance and a soft, lint-free cloth can also be used. Be sure to stop the sink’s drain or use a rubber mat in case the stone comes loose from its setting.

Soft gems, such as pearls, on the other hand, can easily be scratched. GIA suggests using an unused makeup brush instead, and warm, soapy water. Lay the pearls on a towel to dry. The wet string can stretch—and attract dirt—so don’t touch a string of pearls until they are completely dry. Pearls worn every few days should be restrung once a year.

Proper jewelry storage is often overlooked. Jewelry should never be tossed into a drawer or on top of a dresser—that’s a recipe for scratches and fractured gems. Most jewelry pieces come in a box or pouch from the store, which is a perfect place to keep them. Sterling silver, for example, should be kept in an anti-tarnish bag or cloth.

Jewelry boxes that feature individually padded slots for rings, and posts for hanging necklaces and bracelets, are also ideal. Like pearls, opals draw moisture from the air. Storing your opal ring or pearl earrings in a dry area, such as a safety deposit box, can actually do more harm than good. When traveling with jewelry, protect the pieces from scratches or other impact damage by padding the jewelry.

Many jewelry stores offer free check-up or professional cleaning at scheduled intervals (once a year is common). GIA recommends consulting a professionally qualified jeweler, such as a Graduate Gemologist, Graduate Jeweler, or Accredited Jewelry Professional.