How to Choose the Perfect Diamond

Buying a diamond is one of the most important decisions a couple will make. Choosing the size and shape along with the style of the mounting are important personal choices. Understanding the characteristics that influence the brilliance, beauty and value of diamonds can make your buying experience more enjoyable and more fulfilling. Diamonds are like people—no two are ever exactly alike. Very subtle differences in the internal and external characteristics of each stone, along with subtle variations in color and cutting proportions, have a measurable effect on the value of two diamonds which may appear to be similar. Start with a good jeweler, one who’ll take the time to help you through the 4 Cs—cut, color, clarity and carat weight. Understanding the language of diamonds will put you more at ease in making your selection. The next step should be obtaining a diamond certificate from a reputable independent gemological laboratory. The certificate identifies and evaluates specific characteristics that determine the value of the stone you select.

THE 4 Cs


Cut actually means two things: the shape of the diamond (round, marquise, pear, oval, heart, emerald, princess, radiant, etc.) and the proportions of the stone. When a stone is cut to good proportions, light is reflected from facet to facet, then dispersed through the top. The better the cut, the greater the sparkle, brilliance and fire of the stone.


Most diamonds look colorless. But there are subtle shade differences that range from colorless to yellow/brown. Diamonds are graded on a color scale that ranges from D (colorless) to Z (yellow/brown). Diamonds with no hint of color at all are extremely rare and are therefore, most valuable. Most gem quality stones appear to be colorless, but they usually have at least a hint of color.


Almost all diamonds contain a combination of internal and external characteristics called inclusions and blemishes. Normally, they are too minute to be visible without powerful magnification. Some are even so small they require great skill and time to locate. The number, type, location, visibility and color of inclusions determines a diamond’s clarity and may influence its value.

Carat Weight

Like all precious stones, the weight or size of a diamond is measured in carats. A one carat stone is equal in weight to one hundred smaller units called “points.” Therefore, a fifty-point diamond, for example, is the same as a half carat. Carat weight is the most obvious factor in determining a diamond’s value, depending on the quality of its cut, clarity and color.

Grading Colored Stones

Gemstones are the most fascinating natural objects on earth. Ancient historical records show that primitive peoples adorned themselves with gems and believed that gems had magical powers. Some societies even used powered gems for medicinal purposes! The classification of gems in ancient times was mainly associated with color. In other words, all red stones were once called "ruby," all green stones were called "emerald," and all blue stones were called "sapphire." Today people wear gems for many different reasons, including fashion, sentiment, and prestige. As gems became associated with money, the need for accurate identification grew.

The introduction of manmade gems and imitation materials in the 1800`s created an urgent need for experts who could separate the genuine from the fake. The invention of the first cultured pearls and green-glass emerald imitations in the early 1900`s further created need for gemological expertise. Today virtually all gemstones, including diamonds, have a number of manmade counterparts and imitations.

The 4 C`s of Colored Gemstones

Colored stones are graded in a similar way to diamonds. Color, clarity, cut, and carat weight are the main value factors. The difference is that these factors are evaluated and weighted somewhat differently than in diamonds. Diamonds are assigned very precise grades for color, clarity, and cut. In colored stones, color is the main consideration. Unlike with diamonds, a minor clarity difference rarely affects the price of colored stones.


Color in gemstones normally results from the presence of small amounts of trace elements. Some of these coloring agents are an essential part of the gem`s composition, while some are introduced as an extra element when the gem is forming in the earth. Regardless, these elements are responsible for the amazing variety of colors we see in the many different gemstones. Even diamonds appear in virtually all colors of the rainbow. Generally, the more pure and intense the color, the more desirable and more valuable the stone will be. Once again, a top color is more important than a top clarity.


The internal purity or clarity of a colored stone is secondary to the color quality. Clarity characteristics are often a beautiful part of a colored stone--and a key to identification. Collectors even value some colored stones for unusual inclusion scenery. In fact, inclusions can actually increase the desirability and value of certain colored stones. They do this by creating what is called "phenomena." An example of highly valued and beautiful phenomena in colored stones is the star appearance in sapphires and rubies, which results from the presence of intersecting "needles" of the mineral rutile. The cat`s eye phenomena in tiger-eye quartz is the result of a similar condition, except the inclusions are lined up in a parallel manner. The value of certain colored stones, however, can be diminished by the presence of inclusions, when those inclusions are so numerous that they interfere with the passage of light through the stone and make it look cloudy.

Cut and shape:

Colored stones are cut into a wider variety of shapes and proportions than diamonds are. Where the round brilliant-cut is most popular for diamonds, other shapes are better suited to show off a colored stone`s beauty, such as oval, cushion, pear, marquise, emerald cut, cabochon, mixed-cut, trapezoid, and tablet. Each cut is chosen to show off the best color and preserve the most weight from a colored stone. Colored stone proportions also differ radically from those of a well-cut diamond. The bulk of a colored stone may be on the bottom where it has the best chance of returning the most brilliance and best color to the viewer. Certain colored gems look better in some cuts than in other. For instance, the majority of fine quality emeralds are cut in the traditional emerald cut shape. Opals are always cut with a smooth curved top (en cabochon). Fine quality rubies and sapphires are normally cut in oval or cushion shapes.

Carat weight:

The weight of diamonds and colored stones is expressed in carats. One carat consists of 100 "points" and is equal to 0.200 grams.

Gemstone Education


Alexandrite is a rare gemstone that is part of the chrysoberyl species. The color changing crystals are called alexandrite. Generally, but not exclusively, alexandrites are green in daylight and red-purple in artificial light. This gemstone was first discovered in Russia on the sixteenth birthday of Alexander II, and is the birthstone for June.


Amethyst is a crystalline quartz in shades of purple, lilac, or mauve. The ancient Greeks believed it protected you from drunkenness. It is considered the finest variety of quartz because of its pleasing color. It is usually heated to enhance the color. Amethyst is the birthstone for February. Aquamarine Aquamarine is a member of the beryl family. In Latin the name means "water of the sea." The rich deep blue color is considered the most valuable. The intensity of color and clarity are the most important factors when evaluating aquamarine. Heat is often applied to enhance color. Aquamarine is the birthstone for March.

Chrome Diopside

Chrome Diopside gets its color from the element chromium. It is not known to be treated. In 1988 this new green gem began to appear in Europe. The top gem mines are located in Russia. It is a vivid green with great sparkle. It is a great choice for earrings and pendants, as it does not stand up to heavy wear and tear.


Citrine is a variety of quartz that varies from light yellow to reddish-brown. It is usually heated to enhance the color. The citron fruit is the source word for this gemstone. It can be the birthstone for November.


Emerald is a gemstone and a variety of the mineral beryl. Most emeralds are treated with oils to improve their transparency. Rulers and royalty utilized the emeralds alluring green hues for over 4,000 years. Eye-visible inclusions are considered common and expected. Most emeralds are mined in Columbia and Zambia. Emerald is the birthstone for May.


A group of silicate minerals that have been used since the Bronze Age as gemstones. They come in virtually all colors. Many deposits within the United States produce fine gem quality. Garnet is the birthstone for January.


Iolite is a mineral silicate cordierite in the blue or blue-violet variety. This naturally beautiful gemstone is fairly new to the jewelry market. Because of its hardness, iolite is one of the most difficult stones to cut. it is mainly mined in Sri Lanka.


Onyx is a banded variety of chalcedony. Dying onyx is common and expected. the bands range from white to almost every color. Onyx is formed in the gas cavities of lava. It is usually cut as a cabochon or cameo.


Opal is a hydrated amorphous form of silica; its water content may range from 3% to 21%. The internal structure of precious opal makes it diffract light. It varies in optical density from opaque to semi-transparent. Most opal is found in Australia. Opal is the birthstone for October.


Pearl is a hard object produced within the soft tissue of a mollusk. It is made up of calcium carbonate. The ideal pearl is perfectly round and smooth, but many other shapes occur. Over a hundred years ago a Japanese business man, Kokichi Mikimoto, started culturing pearls and helped launch pearls into the gemstone industry.


Peridot is gem quality olivine, a silicate mineral. One of the few gemstones that occur in only one color - variations of olive green. Peridots with high iron content are the deeper green colors. The United States is a major source for peridot. It is the birthstone for August.


Quartz is the second most abundant mineral in the Earth`s continental crust. It belongs to the trigonal crystal system. Its uses and influences on history are as numerour as its colors. It has the unique ability to hold a charge. This natural form of silicon dioxide is found in an impressive range of varieties and colors.


Ruby is a pink to blood-red gemstone, species corundum. It has been one of the world`s most valued stones. Prices are determined by color, the most valuable being blood red. After color, the value is determined by clarity. The clearer the ruby, the higher the price. A ruby without any needlelike inclusions may be treated. Ruby is the birthstone for July.


Sapphire is the blue sister of ruby. Ruby and sapphire are the same material, the mineral corundum. It is the second hardest gemstone after diamond. The most valuable possess an intense blue, sometimes referred to as "cornflower" or "ceylon sapphire." These are generally lighter violet blue. Sapphires also come in a variety of other colors. Sapphire is the birthstone for September.


Tanzanite was discovered in 1967. It is the blue-purple variety of the mineral zoisite. Tanzanites possess a rare and unique quality that gives it the ability to exhibit more than one color. One can see varying degrees of blue and purple. It can only be found in Tanzania and was named by Tiffany. It is the alternate birthstone for December.


Zircon is a silicate mineral. It is a brilliant gemstone whose fire can rival that of a diamond. Zircon is often seen in blue but is also seen in gold, white, orange and green. Brown zircon is usually heated to create blues, reds and some yellows. Brown is also heated to make white zircon.

©This information is provided by E.G.L

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