No discussion about buying diamonds in any form is complete without discussing the classic "FOUR C's" of: Clarity, Color, Cut, and Carat weight. Understanding such criteria as diamond grading reports and the factors affecting a diamond's cost (price) will also prove beneficial for increasing the buyer's confidence level that he or she is making a sound decision.
1. Clarity. Clarity measures the relative viability of external blemishes or internal imperfections (inclusions) naturally occurring within a diamond as evaluated by a qualified gemologist. The clarity scale (GIA) is divided into six primary categories:
a. Flawless (F or FL) - no discernable surface blemishes or inclusions visible when viewed at 10x magnification.
b. Internally Flawless (IF) - insignificant surface blemishes and no internal defects visible at 10x magnification,
c. Very, Very Slightly included (VVS-1 & VVS-2) - extremely difficult to very difficult to find surface blemishes or minute inclusions at 10x magnification, but can be more readily seen at 10x once located at 20x magnification,
d. Very Slightly included (VS-1 & VS-2) - difficult to somewhat easy to find surface blemishes or minor inclusions at 10x magnification,
e. Slightly Included (SI-1 & SI-2) - Easy to very easy to find surface blemishes or readily noticeable inclusions at 10x magnification, but will usually appear to be "eye clean" without magnification. If the inclusions are positioned in the body or close the surface of a SI-2 graded diamond typically the inclusions are slightly visible without magnification. This is typically the opposite with SI-1 graded diamonds, where inclusions are typically invisible without magnification regardless of their positioning.
f. Imperfect (I-1, I-2, I-3) - Surface blemishes or obvious inclusions are somewhat difficult, easy, or very easy to find with the naked eye, especially after being located with 10x magnification. I-2 inclusions effect the diamond's aesthetic appearance (beauty) or durability (potential for cracking), I-3 inclusions effect both.
Diamond prices increase dramatically as clarity category lines are crossed. However, SI clarity is generally considered to be the best compromise between cost and appearance, providing excellent value for stones of G/H color and proper proportions (cut). Buyers should exercise caution when making purchases from jewelry merchants who don't know or won't state the clarity of the diamonds offered. Buyers should also be aware that due to the lower value per carat of the small diamonds that commonly make up a diamond jewelry that these diamonds are less tightly graded and broader clarity range (two grades, such as SI-1 to SI-2, or I-1 to I-2) specifications are therefore not uncommon.
2. Color. The color scale is used to evaluate a diamond's internal tint and plays a significant factor in determining its price, colorless being the most desirable. Color is best evaluated in natural light, as high intensity artificial lighting can make the diamond appear to be of a better color grade than it actually is. Larger diamonds should also be examined for fluorescence, as blue photoluminescence will also make the diamond appear to be of a better color grade. GIA Color grades range from:
a. Colorless (D-F) - tint is nearly undetectable to the unaided, trained eye even when compared to the white standard.
b. Near Colorless (G-H) - tint is almost undetectable to the trained eye, but apparent when compared to the white standard.
c. Near Colorless (I-J) - trace of tint is just detectable to the trained eye, but noticeably apparent when compared to the white standard.
d. Faint Yellow to Faint Brown (K-M) - tint is apparent to the trained eye and readily apparent when compared to the white standard.
e. Very Light Yellow to Very Light Brown (N-R) - tint is readily apparent to the unaided, trained eye without comparing to the white standard.
f. Light Yellow to Light Brown (S-Z) - tint is obvious to the unaided, trained eye without comparing to the white standard.
Diamond prices increase significantly as the color scale ascends towards colorless. While "H" color or better diamonds are well presented in either white gold or yellow gold settings, the surfaces of some yellow gold settings may be spot-plated with rhodium (a silver or "white" colored metal six times more costly than gold) to enhance the stone's sparkling appearance. The near colorless grades, "G-H," are generally accepted as providing the best compromise between cost and appearance.
3. Cut. Cut refers to the proportions and shape of the finished diamond, and is the most important element in determining how much light the diamond will reflect. The finished diamond should be symmetrical. The table should be symmetrical, well-centered, and flat, not sloping. The culet should be centered when viewed from the top. The crown and pavilion facets should be properly aligned. And, the girdle should be perfectly round exhibiting a straight edge when viewed from the side. Ideally, the diamond should contain no extra facets, though extra facets may not have a significant adverse impact on its value depending on their shape and placement. From an aesthetic standpoint, a smaller, properly proportioned diamond is generally preferred over an improperly cut stone of greater carat weight and equal price. Acceptable feature proportions are calculated or expressed as a percentage of the diamond's girdle diameter.
A brilliant or round cut diamond has 56 facets in addition to the table and culet surfaces. The "star" facets (8) are the three-pointed, triangular shaped facets which slope slightly from the table and form the top portion of the crown. The "kite" facets (8) are the four-pointed facets spanning the crown surface from the table to the girdle. The "upper girdle" facets (16) are the three-pointed, rounded bottom-edge facets on the crown surface that border the girdle. The "lower girdle" facets (16) are the elongated, three-pointed, rounded top-edge facets on the pavilion surface that border the girdle. And the "pavilion" facets (8) are the elongated, four-pointed facets spanning the pavilion surface from the girdle to the culet.
Cut also affects the "fire" or "brilliance" exhibited by a diamond. Diamonds that are cut too thin or shallow allow the light to pass through the sides of the diamond and appear lifeless, dull, or flat in the center. Diamonds that are cut too deep or high do not reflect enough light back through the top of the diamond and appear to be dark in the center. Diamonds cut to ideal or within acceptable proportions appear to sparkle when rotated or turned from side to side.
4. Carat Weight and Size. Diamonds weights are measured in carats or fraction of carats called points, with 100 points equaling one carat or two-tenths (0.20) of a gram (i.e. 142, one-carat diamonds would weigh one (1) avoirdupois ounce). Diamond prices per carat weight increase exponentially as the average stone size gets larger given the same clarity and color grades. To determine a brilliant (round) cut diamond's millimeter size (diameter) from its carat weight. The Diamond Size Guide below closely approximates actual Millimeter sizes on an 800 x 640 monitor, however for determining actual sizes a millimeter gauge should always be used.
Round Diamond Size Chart to the Right
5. Cost. The primary factors determining cost are: color, clarity, cut, and carat weight. While cut is important, color, clarity, and carat weight generally influence price to a substantially greater degree. With regards to color, clarity, or carat weight, diamond prices do not follow a linear progression (i.e. a two carat diamond is more than two times as expensive as a one carat diamond) with prices growing exponentially. The heavier, whiter, or less included the diamond the rarer it is in nature. For example: A half carat round (.50ct.) with K-color and I-1 clarity is much more common and 11 times less valuable than the same size IF clarity, D color. All other factors (primarily cut) being equal. An I-1 clarity, K color, 50 point stone would cost about $366.00 while an IF clarity, D color, 50 point stone would cost 11 times as much or $4758.00.
Setting Styles The most popular setting styles are: Prong, Channel, Bezel, and Pave. Though presenting varying degrees of difficulty to the setter, the setting style only minimally impacts the cost of diamond jewelry. A prong setting consists of several (2-6) small metal arms that are notched and bent to hold the stone in place. A channel setting utilizes a narrow metal rectangle, holding the stones in place on the opposite sides or girdle edges. A bezel setting utilizes a metal ring into which the stone is pressed to hold it in place around the girdle.
A pave setting is created by drilling small holes into a solid plate to hold each diamond in place by its cutlet, and then hand-raising small beads of metal with a cutting tool to hold multiple stones (often 4 or more) in place, resulting in a final appearance of being one, much larger stone.
French pave and “U” setting. A style of pave used to set stones in straight or curved rows. French pave utilizes extra cuts and creates a “faceted” look to the metal around the diamond.
Not all setting is created equal. A talented/seasoned diamond setter with ten to twenty years experience can charge 5 times as much as the novice with two or three years experience. Uneven spacing, unequal prongs, prongs that are too light or too heavy are all characteristics of inexperience. The look and the longevity of the setting are all dependant on the setters ability and talent. Manufacturers that focus on cost savings over quality typically end up with finished jewelry that loose diamonds and have a look of inferior craftsmanship especially after the diamonds are worn for a period of time and have lost their luster.
January - Garnet. The garnet derives its name from the Latin word " granatum ," meaning pomegranate because the crystals bear a resemblance to the fruit. According to legend, Noah used purple garnets to light his Arc. Ancient warriors believed that garnets brought victory. The Egyptians wore them in this life - and beyond, taken into tombs with the dead as payment to the gods for safe passage through the nether world. In the Middle Ages, people wore garnets to protect against demons, poisons, wounds and bad dreams - and even cured depression. They were thought to relieve fever, hemorrhages and inflammatory diseases. A lion carved on a garnet several inches long was carried for protection while traveling. In the 12th Century, the Crusaders wore them for protection against wounds and accidents. Conversely, Asiatic warriors believed that glowing garnets, which they used as bullets, could inflict more damaging wounds.
Although "red" is the color most associated with the garnet, it exists in a variety of colors - from black and colorless to many shades of green and red. This array of colors comes from metals such as manganese, iron, calcium and aluminum. Green garnets - which were prized by Russian czars for their entrancing beauty - are the most valuable because they are so rare; followed by colorless and pure red. Today, some believe that garnets help create a power shield against muggers and people with bad intent. Others believe that the garnet is a healing stone, relieving skin irritations and inflammations and regulating heart and blood flow. Whether set in a ring, pendant, earrings or bracelet, this much is true - January's birthstone symbolizes a light heart, loyalty and lasting affection.
February - Amethyst. The birthstone for February is the very popular amethyst. This entrancing gem, a member of the quartz family, derives its name from the Greek word " emthystos ," meaning "not drunk." According to Greek mythology, Bacchus (the god of wine) became angry at Diana the huntress. Bent on revenge, he vowed that the next one to cross his path would be eaten by tigers. A lovely young maiden named Amethyst was en route to worshipping at the shrine of Diana - and called upon the goddess to save her. Diana transformed into a pure white, sparkling image of stone. Bacchus, feeling guilty and repentant, poured grape wine over her - giving the stone its trademark violet hue. In light of this myth, it is understandable why people once believed it prevented its wearers from becoming intoxicated. In ancient Rome , many wine drinkers used amethyst cups to prevent overindulgence.
Amethysts can be traced back to 25,000 years ago in France - where they were used as decorative stones. Early Egyptians believed amethysts possessed good powers, and put them in the tombs of pharaohs. Cleopatra is said to have worn an engraved amethyst ring. Arabian mythology held that amethysts protected the wearer from gout and nightmare. In the Middle Ages amethysts were used as medication - and believed to sharpen thinking, dispel sleep, protect from sorcery and bring victory in battle. It's also said to be the stone of Saint Valentine - that he wore an amethyst engraved with the figure of Cupid, his assistant. And the amethyst, with its purple and violet hues, was a chosen stone of royalty, representative of power.
Today, some wearers believe that amethysts can help with more increased spirituality, restful sleep, pleasant dreams, safer travel and repelling negativity - and is considered a symbol of security, sincerity and peace of mind.
March- Aquamarine. The name "Aquamarine," the first birthstone for March, is derived from the Latin word for "aqua" - water, and "mare" - "sea" because the color of this alluring gem mirrors the beautiful blue hues of the earth's abundant waters. The first documented use of aquamarines is by the Greeks around 300 B.C., where aquamarine amulets were engraved with the god Poseidon on a chariot. Aquamarine beads have been found in the tombs of ancient Egyptians, another gem used to ensure safe passage through the next world. King Solomon's breastplate is said to have contained an aquamarine gem. Two thousand years ago, Emperor Nero is said to have used the gem as an eyeglass - and people believed the gem possessed medicinal and healing powers. In the Middle Ages, it was considered an antidote to poison - and it has been used for telling fortunes.
These bewitchingly blue-hued gems were thought to have originated from the jeweled caskets of sirens that washed ashore from the ocean's depths. Neptune, the Greek god of the sea, considered them sacred. This tie with the sea made aquamarine the sailors' gem, and it became associated with prosperous and safe voyages and protection from danger and sea monsters.
Aquamarines vary in color from deep blue (the most prized) to blue-greens of varying intensities - resulting from traces of iron. Naturally occurring deep blue stones are the most rare and highly prized. This gem is a form of the mineral beryl - that also includes gemstones such as the emerald, morganite and heliodor.
April - Diamond. April's birthstone has been treasured since antiquity - and remains an enduring symbol of lasting love. The ancient Greeks thought that diamonds actually were minute fragments of stars. Hindus believed they originated from bolts of lightning. Others believed they provided invincibility and kept illness and evil spirits at bay.
Diamonds, the hardest of all the gems, are crystals - and crystals are the ultimate form of symmetry in nature. There are several types of diamonds - transparent, translucent and opaque, ranging from colorless to sooty black. Transparent diamonds - either colorless or tinted - are used in jewelry. Translucent and opaque diamonds are frequently utilized in industry.
A diamond's color is related to the level of impurities embedded within it. For instance, yellow diamonds have small quantities of nitrogen; diamonds with bluish undertones contain boron.
When choosing diamonds of measurable weight, it's wise to consider the 4 C's - carat, color, clarity and cut.
May - Emerald. May's birthstone mirrors the green of spring - and has long been prized for its entrancing beauty. Its name derives from the Greek word " smaragdos ," referring to several types of green stones. Emeralds were desired by royalty in Egypt and Babylon, used in tools traced back to 1300 B.C. - and attributed with an assortment of curative powers such as preventing epilepsy, stopping bleeding, curing dysentery and fever and preventing panic. Ancient Romans dedicated emeralds to the goddess Venus because they symbolized nature's reproductive powers. Early Christians associated them with the resurrection. In the Middle Ages, believers thought they held the power to foretell the future.
Emeralds can range in color from light to very deep green, and belong to the beryl family of minerals that also includes aquamarine, heliodor and morganite - and most contain inclusions like diamonds. Very rare transparent emeralds may in fact be even more valuable than diamonds.
Today, May's birthstone is a symbol of love and rebirth, and the emerald's vibrant green color is the perfect reflection of spring.
June - Pearl and Alexandrite. June's first birthstone - the pearl - epitomizes the exquisite beauty of nature unadorned. Indian mythology spoke of pearls as dewdrops from heaven that fell into the sea. They were then caught by shellfish under the first rays of the rising sun when the moon was full. Warriors in India filled their swords with pearls to symbolize the sorrow that a sword brings. As far as 2000 B.C. in China , pearls were believed to have medicinal uses - until the 17th century, pearls were widely used medicinally throughout Europe . In the Middle East , it was believed that pearls could cure many diseases - including mental illnesses. And in fact, low-grade pearls are still ground up and used as medicine in parts of the Orient to this day.
Pearls are created within certain species of oysters and clams. Some are found naturally in mollusks in both salt and fresh water, but many are cultured - raised in oyster farms. They are made mostly of aragonite, a carbonate material that also comprises the shells of mollusks.
A pearl is created when a minute fragment of rock, sand or a parasite enters the oyster or clam. It irritates the mollusk, which then responds by coating the foreign material with layers of shell material. Pearls that are formed on the inside of the shell usually are irregular in shape; those that are formed within the tissue of the mollusk are either spherical or pear-shaped.
A pearl's color depends on the species of mollusk that produced it, and where. When we think of pearls, white usually comes to mind - but pearls also are available in shades of black, cream, gray, blue, yellow, lavender, green and mauve. Black pearls are found in the Gulf of Mexico and parts of the South Pacific; Sri Lanka and the Persian Gulf are famous for cream-colored pearls - and Japan is renowned for its cultured pearls.
June's alternate birthstone, alexandrite, derives its name from Prince Alexander of Russia - who later became Czar Alexander II in 1855. This intriguing gem was discovered in an emerald mine in Russia on the prince's birthday in 1839 - and became popular there since it mirrored the Russian national colors of green and red.
This gem is mercurial in its appearance - in the light of day, it possesses a greenish hue, sometimes with blue or brown undertones. Under artificial lighting, however, it appears violet or reddish-violet.
Since Alexandrite is rare, it is very expensive. Today, it is mostly found in Sri Lanka ; some stones have also been found in Brazil , Malagasy, Zimbabwe , Tanzania and Burma . Synthetic Alexandrite is reddish hued with a tinge of green; attempts thus far to mirror the intriguing "color change" of natural Alexandrite have not been successful.
July- Ruby. July's birthstone has been treasured through the ages for its rare beauty, and continues in the 21st century. Since large rubies are more difficult to find than large diamonds, sapphires and emeralds, a ruby's value increases with size more dramatically than any other gemstone. And like diamonds, rubies are evaluated on their color, clarity, cut and weight.
The name is derived from the Latin " ruber ," meaning red. Once believed to contain the spark of life, in ages past rubies were thought to be self-luminous. In the Orient, they were called the "glowing stone" or "lamp stone." Hindu priests believed that huge emeralds and rubies lit up the homes of the gods. And Greek mythology spoke of a female stork who repaid the kindness of Heraclea by bringing her a radiant ruby that was so incredibly bright that it lit her room up at night. In the Middle Ages, rubies were believed to bring the wearer good health, cure bleeding, and guard against evil thoughts, lust and discord. They were also thought to have the power to warn of imminent troubles, illnesses and death; when the stone darkened, so did a person's sunny outlook about the immediate future. Rubies (along with sapphires) are a form of the mineral corundum. Red corundum is referred to as ruby, all other corundum gemstones - from orange and yellow to green and violet, are called sapphires.
August - Peridot . The month of August is the stone peridot , which was called the "evening emerald" by the Romans, ranges in color from light olive to deep green. One of the oldest gemstones known to mankind, in ages past it was considered a symbol of the sun. The Greeks thought it imbued royal bearing upon a person wearing it; in the Middle Ages it was used to ward off evil spirits. Turkish sultans collected an astounding collection of peridots - and in the Topkapi museum in Istanbul , a throne is on display with 955 peridot cabochons. Since crystals of peridot can be found in volcanic rocks, Hawaiian legends call peridot the tears of the goddess Pele . Other attributes associated with it included marital bliss, eloquence and serenity.
September - Sapphire. Sapphires, September's birthstone, derives its name from several ancient languages. " Sappheiros " is Greek for the island of Sappherine , where sapphires were found in ancient Greece . In Latin, " sapphirus " means blue. The sapphire was the gem of Apollo, the Greek god of prophesy - so worshipers seeking his help wore them when paying homage at his shrine. And according to lore, the ancient Persians believed that the earth rested on an enormous sapphire - and that its reflection gave the sky its color and called them the "celestial stone." In the Middle Ages, sapphires were considered channels to the Oracles and one of the few stones allowed in holy jewelry.
The stone was once representative of a pure soul and regarded as a symbol of truth and sincerity. Up until the Middle Ages, priests wore sapphires to protect against impure thoughts and carnal temptations. It was also believed to protect wearers from harm, envy, infidelity and snakes - and ensure safe travel.
This relative of the ruby is also a form of the mineral corundum. Ranging in color from palest blue to deepest indigo, sapphires which are medium to deep cornflower blue are the most prized. You can find "fancy sapphires" in many other colors and tints - including colorless, gray, yellow, pale pink, green, orange, violet and brown.
October - Opal and Tourmaline. October has two birthstones - opal and tourmaline. The mercurial opal derives its name from the Latin " opalus ," which means "precious stone." The ancient Romans considered opals a symbol of love and hope. In the Orient, they were called "the anchor of hope." In Arabia, people believed that opals fell from the skies in flashes of lightning - and since they were believed to have the power to make the wearer invisible, opals became the gem of choice for spies and thieves.
In Medieval times, people believed that when an opal changed color, it indicated whether the wearer was in good or poor health. They also believed opals could keep the heart healthy, protect against infection and prevent fainting. However, perceptions changed midway through the 14th century, when the Black Death decimated Europe . People believed that opals were the cause of this horrific plague - and noted that the stone would change appearance and lose its luster when someone died. This change was due in fact to the opal's sensitivity to changes in temperature.
Opals are exceptionally mercurial in color; like capturing the colors of a rainbow in one stone. Of all the colors of opal, black is the most valuable, followed by crystal, white and milky opals.
Tourmaline derives its name from the Sri Lankan word " tourmalli ," which translates into "something little out of the earth." It can be found in a variety of colors - and in the past has been mistaken for sapphires, rubies and emeralds.
You can find tourmaline in a veritable array of colors - from yellow, green and red to blue, pink, brown, black and bi-colored. It's known as the "peace stone" - and some believe it has the ability to alleviate fear and produce a calming effect.
November - Topaz and Citrine. November's first birthstone, topaz, may have derived its name from the Sanskrit word for "fire." Another origin may have been the Island of Topazos in the Red Sea . In ancient times, people believed that this stone could actually control heat - and that it could cool water, rage and cure fevers. The early Egyptians thought that the sun produced the stone's warm golden glow - and the Greeks believed it enhanced strength and made its wearer invisible when trouble arose. It was also believed that carving a figure of a falcon on topaz would engender the good will of those in power. Others believed that topaz cured insomnia, lifted the spirits, strengthened the mind and increased wisdom. Powdered topaz was added to wine to prevent asthma and insomnia. During the Middle Ages, topaz was in great demand with the clergy and royalty.
Topaz can be found in a range of colors - from blue, pale green and yellow to pink, red, brown and black. Pure topaz, however, is colorless - and can be mistaken for a diamond. The rarest and most valuable color of topaz is red.
Citrine, November's second gemstone, gets its name from the French word for "lemon." In ages past, people carried it as protection from snakes and evil thoughts.
This affordable gemstone - which is a form of golden quartz - can be found in colors ranging from bright yellow and gold to orange and orange-brown. The darker, more orange shades are sometimes referred to as Madeira citrine. Today, citrine is associated with hope, youth, health and fidelity.
December - Turquoise, Blue Topaz, Tanzanite, and Zircon. December has no less than four birthstones associated with it - turquoise, blue topaz, tanzanite and zircon.
The name "turquoise" is thought to have originated from the French phrase " pierre turquoise" - which means Turkish stone. Merchants from Venice brought to Europe turquoise which they had purchased in Turkey . It ranks among one of the earliest stones known to have been used in jewelry. It's been found in the tombs of mummies dating aback to 5,000 B.C. - as well as in ancient burial sites in South America , Mexico and Central America . The Incas used turquoise to create beads and figurines, and the Aztecs made pendants and masks of it. In the Middle Ages, turquoise was used to decorate vessels and covers of manuscripts.
The Incas used it to create beads and figurines, while the Aztecs crafted masks and pendants of turquoise. And of course, in the American Southwest, turquoise has been a gemstone of choice for thousands of years, popular in necklaces, ear pendants and rings. For them, the blue in turquoise symbolized the heavens, and the green, the earth. Medicine men used turquoise for charms; the Navajo believed that throwing turquoise into a river in conjunction with praying to the rain god would ensure that rain would fall.
Throughout history, an array of superstitions was intertwined with turquoise. Some believed that when it changed color, it would reveal a wife's infidelity. Others thought that a turquoise's color changed with the weather. It was also believed to guard against evil, and bring good luck and love.
Depending on its shade of blue, you'll sometimes find blue topaz referred to as "sky blue," Swiss blue" and London blue," with London blue being the darkest. At first glance, blue topaz is often mistaken for aquamarine. This alluring stone is sometimes found naturally, but more often is silver topaz which has been irradiated and heat treated to produce its blue color.
December's third birthstone is zircon. Its name derives from the Arabic for " zar " (meaning gold) and "gun" (meaning color). Arabians in ages past were enamored with the orange-red and reddish brown hues. Later, it was believed to protect travelers against injury, disease and insomnia. During the Black Death plague of the 14th century, zircon was thought to offer protection from its ravages. It was also believed to help insomniacs sleep, provide an antidote to poison and as an aid to digestion.
Zircon can be found in a variety of colors - but in its natural form appears colorless to pale yellow or green. A created color - "starlight blue" - debuted in the 1920s, created by heating golden brown and yellow zircon. Red is the rarest and most valuable color of zircon, followed by blue. Less expensive are the colorless, orange, brown and yellow.
Tanzanite has become so popular that in October of 2002 the American Gem Trade Association (AGTA) announced that tanzanite had joined zircon and turquoise in the list of birthstones for the month of December. The legend of its discovery: a short lived grass fire caused by a lightening strike was the catalyst that turned Zosite into vibrant blues. These glowing colors were spotted by Massai herdsmen. While a romantic story, it is regarded as unlikely that enough heat could be generated by such a fire to affect such a transformation. The gemstone of Tanzanite exudes sophistication; the quintessence of class; at the same time Tanzanite speaks of individuality and self-confidence. Tanzanite Jewelry is suited to all ages, emphasizing non-conformity of the young and sophistication of the mature.
Understanding these eight common terms will be helpful when comparing values and buying diamonds.
(1)"Carat" is a unit of weight measurement used for weighing diamonds. One (1) carat equals 0.2 grams or 200 milligrams, five (5) carats equal one (1) gram. 142 carats equals one (1) avoirdupois ounce.
(2) "Point" is a unit of weight equal to 1/100 of a carat, 100 points equaling one carat, and written as 1.00 carat.
(3) "Table" is the flat top surface of a cut diamond. Table diameter is considered acceptable when between 51.4-66.0% of the girdle's diameter.
(4) "Crown" refers to the upper domed surface above the girdle of a cut diamond. The angle of the crown between the girdle and the table is considered acceptable at between 30.0-37.0 degrees. Crown height is considered acceptable when between 11.0-16.2% of the girdle's diameter.
(5) "Girdle" refers to the edge where the crown and pavilion of a cut diamond meet, marking the maximum diameter or width of the diamond. A girdle width of between 2.0-4.0% of the girdle's diameter is considered acceptable. Too sharp or thin a girdle increases the likelihood of chipping.
(6) "Pavilion" is the tapered under half or base of a cut diamond below the girdle. The angle of the pavilion from the girdle to the culet is considered acceptable when between 39.7-41.7 degrees. Pavilion depth is considered acceptable when between 41.5-45.5% of the girdle's diameter.
(7) "Culet" is the end point of the pavilion, finer being considered better, however a sharp point is susceptible to chipping.
(8) "Girdle Diameter" is the diameter of the diamond at the point where the crown and pavilion meet. Other dimension characteristics of a cut diamond are expressed as a percentage (%) of the girdle diameter.
GOLD ALLOYS. Because 24 karat, pure gold (24/24 = 100% gold) is very soft, wears away very rapidly with ordinary use, and is considerably more expensive than harder gold alloys; it is rarely used for making gold jewelry. 22 karat gold (22/24 = 91.7% gold) is also of poor durability and is therefore also less suitable for making gold jewelry than harder alloys. To be legally marketed in the United States as gold, gold jewelry must be at least 10 karat.
Popular alloys that offer increased strength (hardness) and extended wear ability are 18k (18/24 = 75.0%), 14 karat gold jewelry (14/24 = 58.3%), and 10k (10/24 = 41.7%), with such designations usually being stamped on the clasp or inside edge or rim of the gold jewelry item. Gold jewelry items may also be stamped .999 (24k), .917 (22k), .750 (18k), .583 (14k), or .417 (10k) as another way of indicating their karat rating fineness (common in Europe). Though it is relatively unusual today, older items may be stamped "p" or plumb (e.g. 14kp), indicating that they are exactly the 24k, 22k, 18k, 14k, or 10 karat designation.
Price Comparisons, everything else being directly comparable (e.g. link shape, mm or gauge size, gram weight, length, and manufacturing process) 18k gold will be approximately 30% more expensive than 14k gold jewelry and 80% more expensive than 10k gold; and 14k gold jewelry will be approximately 40% more expensive than 10k gold.
Multi-colored gold (yellow, white, pink, green, etc.) is produced by combining different percentages of alloy metals (primarily copper, silver, nickel, and zinc) with gold, but still retains its full 18, 10, or 14 karat gold rating.
Gram Weight. 24k, 22k, 18k, 14k, or 10k gold is weighed in grams and troy ounces (31.1 grams), and though it is becoming more popular, it is still relatively unusual for retail merchants to sell gold jewelry by the gram. While the karat fineness is always well marked, the Client is often left in the dark as to the gold jewelry item's weight, making an informed decision as to the value offered nearly impossible. As a general rule, if the merchant can't or won't state the gram weight of a jewelry piece or mounting, purchasers should exercise greater caution when buying from that merchant.
American Ounces (Avoirdupois) vs. Troy Ounces. Troy weight is a system of units of mass customarily used for precious metals, gemstones, and black powder. It is commonly confused with the avoirdupois system commonly used in the United States for most applications of trade like in grocery stores or the post office. A troy ounce is equivalent to 31.1 grams as opposed to the avoirdupois ounce which is 28.3 grams. When spot gold or gold futures are quoted on a financial exchange, they are always quoted in troy ounces.
