Glossary of Gemstone, Metals, and General Jewelry Terminology
Diamond and colored gemstones can express deep sentiments such as love and promise and eternal connection. You put a great deal of thought into who you are and what a special someone means to you. Putting thought into how you want to convey your intentions is just as important.
When you first begin to explore the world of diamonds and colored gemstones, you might feel a mixture of excitement and overwhelm. Stones and settings are complex. What do you want? How do you know what you’re buying and whether it’s high in quality?
This glossary of gemstone and metal terms will help guide you as you embark on your wonderful journey of gemstone and ring selection.
A series of microscopic nicks along a diamond’s facet junctions, abrasions make edges fuzzy or white rather than sharp and clear.
The AGS, or American Gem Society, is an esteemed trade organization of high-level jewelers. This organization seeks to maintain exacting standards of fine jewelry quality and ethical behavior among professionals. The AGS exists to protect consumers.
The AGSL is the diamond grading laboratory of the AGS. They provide diamond grading reports to protect consumers buying diamonds and gems. All AGS jewelers must sell stones that meet the criteria of the AGSL.
The American Gem Trade Association is recognized as the authority on natural colored gemstones and cultured pearls. The AGTA is involved in all aspects of the colored gemstone and cultured pearl trade: mines, research labs, wholesale, and retail showrooms.
A type of gem coloring that occurs when a naturally colorless stone takes on one or more hues because of impurities in the stone. Emeralds, rubies, sapphires, quartz, and topaz are among the allochromatic gems popular in jewelry.
An alloyed material is a mix of two or more metals, combined to create metals with different properties. Gold is commonly alloyed (24 karat gold is pure gold, while other karats are alloys with different amounts of gold). Sterling silver, brass, and bronze are some of the other alloyed metals in the jewelry industry.
Annealing is a process used by jewelers when working with metals. To anneal is to heat a precious metal to a specific temperature to make it malleable for creating pieces of jewelry.
This is this formal evaluation of a diamond, stone, or other piece of jewelry, often for insurance purposes. The monetary value of the jewelry is established based on a thorough examination of the quality of the stone and more.
An assay is the testing of the quality of a metal or metal alloy in which the material is examined and analyzed for purity and quality.
A unique type of diamond cut, an Asscher cut diamond is square with rectangular facets.
Avoirdupois refers to the weight of an object as well as to selling goods based on weight, such as the carat weight system used to describe the size of diamonds and other gemstones.
This term describes a setting for wedding rings or other stone rings. An azured setting has a square hollow into which the stone will be placed. This allows more light into the stone and enhances the way it reflects lights.
The Brown & Sharp Gauge refers to the measuring of metals in jewelry making. The gauge number can be converted to inches or millimeters, and the lower the number, the greater the thickness of the metal.
A unique diamond cut, the baguette shape is rectangular with four sharp corners, straight sights, and step-cut facets.
A bail is a small but important component of jewelry, typically necklaces. The bail is the pieces that allows a pendant to hang securely and fashionably from a chain.
A ring without a raised setting, usually made of metal. Bands vary in width and style, as some are plain and some are fancy.
Bar Channel Setting
A ring setting in which a diamond or other stone is supported on both sides by a metal bar. When a setting has multiple stones, the bars separate each stone from the one(s) beside it.
This is a cut for diamonds and other gemstones that has different shaped facets: moon-shaped, brilliant, break, and fan.
Base metals are those metals used to alloy metals like gold or Sterling silver. Common base metals include copper, zinc, nickel, platinum and palladium.
This is a type of center gemstone setting, and as such it showcases and protects the stone. Its prongs support the diamond or other gem in a basket shape as well as let light pass through to enhance brilliance.
In this ring setting, the stones are set directly into the metal band. Diamonds or other stones are set closely together and held in place by beads of precious metal.
Spacer beads, often made of metals such as gold, silver, or alloyed. They are available in a broad range of sizes to meet all jewelry-making needs. Sizes are measured in millimeters and refer to diameter of the bead as well as hole size.
Bearding or Girdle Fringes
This is a type of diamond inclusion, or flaw, that looks similar to hair-like lines around the girdle of the stone. Bearding or girdle fringes occur during the cutting process. These flaws are usually minor, but if they are problematic, they are polished away or, in extreme cases, the stone is recut.
Bevel Cut/Biseau Cut
Stones are bevel cut, also known as biseau cut, when they have a large table and a pavilion that is typically step cut or brilliant cut. Stones can be cut in almost every possible shape imaginable with the bevel cut. This cut is most often used with opaque stones.
The eight kite-shaped facets cut around the crown of a brilliant-cut diamond, also referred to as kite facets or main facets.
This setting showcases a center stone. A thin border of precious metal completely surrounds the stone. The metal secures the stone as well as accentuates its beauty.
Black diamonds are a type of colored diamond. Three types of black diamonds exist: natural black diamonds, man-made black diamonds, and treated black diamonds. The true black diamond is the natural black diamond. It has such a high amount of graphite within it that it appears black.
This is an effect seen in round, brilliant-cut diamonds that have deep pavilions. Looking directly through the table makes the center appear black or dark.
A surface imperfection on a stone.
This is an alloyed gold created by combining gold with indium. This gold isn’t used in jewelry designed for direct contact with skin, as sweat can discolor the metal.
The appearance of a bowtie shape across the width of a stone that can be seen when looking straight down on the stone. The bowtie effect can be present in fancy cuts rather than round diamonds. A slight bowtie effect is normal, but a prominent effect is problematic.
A type of setting for holding a diamond or other stone in a ring in which the edges of the setting extend over the top of the stone just enough to hold it in place.
Metal alloys used by jewelers to join pieces of metal together. Copper, nickel, silver aluminum and gold are common brazing/soldering alloys.
Brilliance is the description of the amount of light reflected out of a stone from its table. Brilliance is impacted by the quality of the cut of the stone.
A cut that produces a diamond with 57 or 58 facets. The quality and sheer amount of the facets create a stone from which a great deal of light is reflected. The brilliant cut enhances the brilliance of the stone.
A bruise is a type of inclusion, a flaw under the surface of the diamond. It is usually caused by the stone cutter. A strong blow causes featherlike inclusions to spider down into the diamond.
A diamond’s girdle is the band or rim that runs around the circumference of the diamond. The girdle is said to be bruted when it is left rough and unpolished. It can look frosty, grainy, or rough.
These flaws within a diamond have a bubble-like appearance, but they aren’t actually bubbles. They’re inclusions of different minerals that became trapped in the diamond as it grew.
Gold or silver that is at least 99.5 percent pure and exists in the form of bars or ingots rather than coins.
This furnace is like a kiln and is an important component in the casting process of jewelry-making. The burnout furnace can be used for a quick burnout or for slower, controlled rises in temperature.
Carat Total Weight
The carat is the unit of measurement for a gemstone’s or pearl’s weight. A carat is divided into 100 points for ease of discussion and conceptualization of the weight. A 100-point diamond weighs one carat, while a 50-point diamond weighs a half carat. Along with cut, color, and clarity, the carat is one of the Four C’s of diamond/stone quality.
A stone that has been cut without faceting so that it has a convex top and slightly domed base and then highly polished. Stones that are typically cut this way include opals, onyx, turquoise, moonstone, and star sapphire.
Similar to a cavity in a tooth, a gemstone cavity is a small hole on the surface of the stone. This flaw may not be visible to the naked eye.
This stone is the focal point of the ring. The center stone of a ring with only one gemstone is called a solitaire. In a setting with multiple stones, the center stone is usually bigger than other stones and set apart in some way so it is accentuated.
A unit of measurement in the metric system, a centimeter is equal to 10 millimeters. While diamonds and gemstones are measured in weight (carats) rather than size, it can be useful to have a size reference point. Millimeters are commonly used to express the size of stones, and they can be converted to centimeters.
A jewelry-making process involving the use of molds. When casting with metal such as gold or silver, centrifugal force is needed to force the molten metal completely into the mold. Sharply defined, detailed jewelry is the result.
The certificate, or cert, grading report, or diamond dossier, shows the blueprint of a diamond without its setting. In addition to this blueprint drawing, the certificate discloses important information about a diamond: cut, quality, measurements, and weight in carats.
A jeweler who has completed gemology courses and passed exams and is recognized by the American Gem Society.
A diamond or other gemstone setting in which a row of stones, with nothing between them, is suspended between two parallel walls of metal.
A flaw created when a gemstone is damaged upon striking a hard surface.
Clarity is an official term used in grading polished gems and diamonds. It assesses the presence and degree of inclusions such as particles, cracks, and blemishes. Most stones have some inclusion that happened naturally as the stones formed. Along with carat, cut, and color, it’s one of the Four C’s used in grading gems.
The piece on the ends of a necklace or bracelet that connects and secures the piece of jewelry.
A crack inside a diamond, cleavage can be minor or major. Minor cleavage will have almost no impact on a stone, while major cleavage can compromise the stone’s integrity.
A cloud is a type of inclusion that is simply a small group of crystals the size of a pinpoint. Because they’re so small, they typically don’t affect the diamond. However, in instances where the cloud happens to be large, the appearance of the diamond will likely be impacted.
This type of diamond setting incorporates multiple diamonds, usually round, into a cluster. The result is a ring that has the appearance of a solitaire while sporting many stones.
Cobalt is a metal used in ring bands. It is durable, scratch-resistant, and comfortable to wear. Although the color is similar to platinum, cobalt is described as a bright white metal.
Along with carat, cut, and clarity, color is one of the Four C standards used to grade diamonds. Diamonds that are naturally colored shades of yellow, brown, pink, blue, or green are considered fancy. Colorless diamond are considered to be the most valuable, but your decision to go with color or colorless is a personal preference.
A ring band style in which the edges are rounded to reduce pinching and increase comfort.
Like skin, a stone’s complexion describes its surface appearance based on the presence or absence of blemishes.
A small flaw, such as a bruise or a chip, that occurs in most diamonds as a product of wear.
A soft metal used in jewelry-making, frequently alloyed with gold, bronze, and brass.
This is the angle a gem cutter creates in order to maximize a diamond’s brilliance. The angle allows light to be reflected off the surface of the diamond rather than escaping from within.
The upper facets of a diamond that lead from the girdle to the table.
The lower faceted portion of a brilliant-cut diamond, also known as the pavilion.
The facet at the end of the culasse. The culet is referred to as closed when the culasse tapers to a point and open when it has a flattened surface.
A gemstone cut, usually rectangular with rounded edges, that resembles the shape of a cushion.
Cut refers to the way a gem cutter crafts a rough stone into a polished one. Cut is both art and science, style and precision. A stone must be cut to the correct depth and be faceted correctly in order to reflect light and create brilliance. A cut refers not to shape but to symmetry, proportions, and polish. Cut is one of the Four C’s used in grading a stone, along with carat, color, and clarity.
De Beers Consolidated Mines Limited
Responsible for nearly half (45%) of the world’s gem and diamond mining and for marketing newly mined stones to relevant companies.
An undesirable cut, a deep cut causes light to refract, or escape through, the pavilion instead of being reflected back to the top of the diamond. This reduces brilliance and thus value.
The measurement of a diamond from the table to the culet.
Dividing a stone’s width by its depth as for an important measure of its brilliance.
The measurement of a gemstone’s width taken at the girdle, the widest part of the diamond.
Diamond is a naturally occurring substance growing as carbon crystallizes deep in the earth. It is rough when mined then polished to brilliance by gem cutters. Diamond is the hardest natural substance on the planet.
Diamond Grading Reports
Like a school report card, a diamond grading report is an official assessment and statement of a gemstone’s quality and worth. Jewelry professionals use the 4C’s to determine the grade: carat, clarity, color, and cut.
Diamond Quality Guide
A tool used to help people select diamonds. Quality guides indicate the rating of the 4C’s and/or a scale indicating the degree of inclusions within a stone.
The width and height of a diamond in its setting.
The source of a diamond’s fire, dispersion is the distribution of light as it enters a diamond and reflects off of its cut angles and facets, displaying the colors of the spectrum.
European Gemological Laboratory with worldwide branches, including EGL USA, EGL Asia, and more. One of the world’s largest and most respected organizations for gemstone grading, certification, identification, and research.
A diamond with an emerald shape is rectangular and whose facets are both rectangular and trapezoidal. The corners are cut rather than pointed.
Treatments used to enhance the appearance of the stone, enhancements are made during the cutting and polishing process. In order for a gemstone to be certified, treatments can’t interfere with the natural beauty of the stone. Enhancements must be disclosed to buyers.
Eternity Ring/Anniversary Band
These rings have special significance in a marriage and are given to represent continued love or even to celebrate the birth of a child. Such bands are a narrow band of platinum or gold set with a half- or full circle of diamonds and/or colored stones.
Gem cutters sometimes cut extra facets, facets beyond the requirements of brilliant cut or emerald cut stones, in order to polish away inclusions and blemishes and thus increase clarity. Extra facets might slightly affect brilliance.
F/IF Diamonds (Flawless/Internally Flawless)
Two of the 11 clarity grades on the GIA International Diamond Grading System scale. While a truly perfect diamond or gemstone doesn’t exist, those rated F/IF on the clarity scale come close and show no inclusions even under 10x magnification. A flawless stone has no visible inclusions or blemishes, and an internally flawless stone has no visible inclusions but may have blemishes.
A girdle polished in facets around its circumference.
The small, flat surfaces created by a gem cutter when polishing a gemstone. The facets help shape the diamond or other stone, and they affect brilliance by the way light enters and reflects or refracts from the stone.
Fair Cut Diamond
A diamond that doesn’t reflect enough light, typically because the cut is either too shallow or too deep.
Fancy Color Diamond
Most diamonds are colorless to light yellow, while fancy color diamonds are colored, thanks to tiny amounts of impurities, in the full range of the visual spectrum and can be blue, green, yellow, brown, orange, red, or pink. These diamonds are extremely rare and thus valuable.
Any diamond shape other than classic round is considered a fancy shape.
A fancy yellow diamond is different from a colorless diamond that has a yellowish, and undesirable, tone. A yellowish diamond is near the “Z” end of the D-Z diamond color rating scale; the closer a diamond is to “Z,” the more impure and yellowish it is. Fancy yellow diamonds are yellow colored in their own right, are rare, and are valuable.
Anything that damages the appearance of a diamond and reduces its value: blemishes, scratches, chips, flaws, and more.
A separation or crack on or beneath a diamond’s surface that appears feathery and white, glossy, shiny, or transparent depending on how one looks at it.
These are inclusions that have a wispy, white, and irregular appearance.
An artisan’s tools and materials, such as small, standardized pieces used in jewelry making and repair, such as clasps, lobster claws, ear nuts, and more.
A type of inclusion in the shape of a fingerprint. Fingerprints are rare in diamonds and more common in other gemstones.
The description or rating of a gemstone’s outer quality, including polish and symmetry.
Another term used for dispersion or refraction, fire refers to colored light that is emitted from the diamond.
An unattractive circular flaw within a diamond, fish eye occurs in a poorly cut, too-shallow stone.
A gemstone melee setting, or setting with a row of multiple diamonds or other gemstones, in which the melee is set down into the band with delicate fishtail-shaped cuts.
Typically caused by cleavage opening to the surface of a stone, a fissure is an elongated cleft on diamond or other gemstone.
How a band feels to the wearer.
A term that applies to thin diamond cleavage.
A flaw is an imperfection within a diamond or gemstone. Inclusions, cracks, and cleavage are examples of flaws.
A diamond or other gemstone is considered to be flawless when it has no external blemishes or internal flaws of any sort as viewed by the naked eye and up to 10X magnification. Flawlessness (or, conversely, the presence of flaws) affects the diamond’s clarity rating.
A glow, often bluish but sometimes white or yellowish, that emanates from some diamonds when they are exposed to ultraviolet (UV) light. This characteristic is undesirable when it’s very strong or extremely strong, but when it’s strong, moderate, or faint, it’s not problematic and sometimes even helps improve the yellowish appearance of flawed diamonds.
Four of the important qualities assessed when diamonds are graded: carat, clarity, color, and cut.
A crack or break on or in a diamond or gemstone. Fractures are uneven and often appear feather-like. Fractures negatively affect a diamond’s clarity and value.
A type of enhancement that involves using molten glass to fill a fracture and improve clarity.
A description used for round brilliant cut diamonds, typically the smaller brilliant cut diamonds used in melee. Full cut diamonds have 57 or 58 facets as opposed to the 17 or 18 facets of a single cut diamond.
An instrument used by a gemologist to measure the dimensions and carat weight of diamonds and other gemstones.
The Gem Certification and Assurance Lab (GCAL) is a research and identification lab that grades, and guarantees their grading, diamonds. A GCAL certificate ensures that a diamond truly possesses the stated quality of cut, color, clarity, and carat measurements.
A gemologist is someone who has completed a regimented course of study and, usually, earns special certification in gemology. A gemologist is an expert who knows the properties of gems, studies their internal structures as well as their surfaces, and can identify, analyze, and evaluate gems.
The scientific study of precious gems.
A gemstone is a precious stone regarded as beautiful—based on both scientific and aesthetic properties—and durable and thus is cut and polish for jewelry or decoration. Most gemstones are minerals, but a few, such as pearl and amber, are organic.
The Gemological Institute of America is an organization dedicated to science, research, academics, and general high standards in gemology. The GIA created the Four C’s diamond grading system.
The narrow band circling the widest part of the diamond.
The measure of how wide this band circling the diamond is, girdle width affects the quality of the diamond. If the girdle is too narrow, the diamond is at risk for cracking and breaking, but if it’s too wide, the stone’s brilliance and fire are reduced.
A soft, yellowish precious metal that is very malleable and ductile. It can be pure (24 Karat) or alloyed with other metals such as silver or copper. Alloying gold makes it harder as well as less expensive.
Good Cut Diamond
The GIA grades diamond cuts as excellent, very good, good, fair, and poor. A good cut diamond has brilliance where poor and fair cuts do not. However, they don’t possess exceptional brilliance and fire as do the higher grade cuts. A good cut offers beauty at a reasonable price.
Assessing and evaluating a gemstone’s quality based on the 4C’s and other measurable factors.
When stones within a setting incrementally increase or decrease in size, they are described as graduated.
A unit of weight in the metric system; one carat is equal to 0.2 grams.
Gold alloyed with silver has a green gold color. The higher the karat of the gold, the better the green gold color.
Growth or Grain Lines
When irregular crystallization occurs while a diamond is forming, grain- or growth lines appear. Small, colorless lines don’t affect the clarity of a stone, but grain lines that are large, colored, or white lower a stone’s clarity grade.
A guard ring, with or without stones, is worn in front of a ring to protect it from slipping. Often, wedding rings are surrounded by two guard-rings.
A setting frequently used in men’s rings in which the stone is set down into the metal of the band.
A thin, hair-like internal flaw (inclusion).
Hardness refers to a mineral’s ability to resist scratches (it is not, however, a measure of its ability to resist breakage). The measurement of hardness reveals a mineral’s place on the 10-point Mohs scale where the higher the number, the more scratch-resistant a mineral is. Diamonds are a 10 and are the hardest known natural substance.
HARMONY Recycled Precious Metals
HARMONY is a brand offering engagement rings, wedding rings, and other eco-friendly jewelry. Old precious metals are melted, cleaned, alloyed, and made into new bands and other jewelry items.
The part of the setting that holds the gem in place with a basket and prongs.
The shape of the part of the setting that holds the stone is determined by the shape of the stone as well as the style of the setting.
Head Size Range
Typically based on carat weight, the range of stone sizes that can be secured by a given setting.
A fancy-cut diamond shaped like a romantic heart.
The part of a necklace clasp that is shaped like a fishing hook around which the round eye of the other end of the necklace fits.
The description of a stone’s color that indicates the purity of the color. If a stone’s color is blue, its hue indicates the presence of other colors in addition to the main blue color.
I1/I2/I3 (Inclusions Visible to the Unaided Eye)
Clarity Grade I diamonds are included, or flawed. The subcategories are I1, I2, and I3. While all are imperfect, I3 graded diamonds have inclusions that are greater in number and/or size that can very easily be seen with the naked eye. I1 inclusions might be seen with the naked eye and are easily detected under 10x magnification.
This is a grade of cut that is exceptional in its ability to let light enter and reflect back, creating brilliance and fire. A stone’s proportions, polish, and symmetry are analyzed to grade the cut. The Ideal grade is above very good and below Ideal Plus.
International Gemological Institute. The IGI examines and grades gems in order to issue a detailed certificate detailing the characteristics of every stone they examine in order to aid both diamond buyers and sellers.
International Gemological Laboratories. The IGL analyzes, grades, and certifies stones.
A setting, usually of faceted or polished white gold, that is designed to give the illusion that the stone is bigger than it is. The band surrounds and enhances the stone.
Sometimes referred to as birthmarks, flaws can be found within the stone (inclusions) or on the surface of the stone (blemishes). Many different types of imperfections exist.
Flaws within the diamond of varying sizes and types that affect a stone’s clarity grade.
While diamond weight is measured in carats, and to many people “carat” indicates size, the actual size of a diamond is measured by its average girdle diameter in millimeters.
Stress within a diamond due to inclusions or structural irregularities.
A metal frequently alloyed with platinum to make the platinum more workable.
Stones that lack symmetry and external form.
Along with the catch and pin-stem, the joint helps attach a brooch or pin to clothing. The joint is the component that holds the pin-stem and moves the pin toward or away from the catch.
Not to be confused with “carat,” which is the weight of a stone, karat is an indicator of the amount of gold that comprises something metal such as a ring band. Pure gold is 24 karats. The lower the karat number, the less the amount of pure gold in the alloy.
A diamond flaw in which a crystal extends from within the diamond to the surface.
Laser Drill Hole
A small hole created in a stone when a laser is used to drill into the diamond to remove a small inclusion, typically a crystal.
This outdated term was once used to describe diamonds lacking brilliance and fire.
A process used to remove or minimize the appearance of inclusions by lightening them.
Different than depth, length is a surface measurement, in millimeters, of the top of the stone.
Used with fancy shapes only (shapes other than round), the length-to-width ratio indicates how much longer a stone is than it is wide. It is an analysis of the outline of a fancy shape rather than a value judgment.
Lobster Claw Clasp
A classic clasp used to attach the ends of bracelets and necklaces, this clasp involves a spring mechanism to open the clasp in order to hook the catch on the other end.
One of the specialized tools of jewelers, a loupe is a small magnifying glass.
A rating on the clarity scale for colored gemstones. Loupe clean is the highest grade and describes a gem that is internally flawless (IF).
The light reflected from a gemstone’s surface.
One of the components, along with shape, of the cut of a diamond, make refers to the quality of the cutting and faceting: polish, proportions, symmetry.
A property of a metal that refers to its ability to be shaped and formed without breaking.
A jeweler’s tool used in making rings, earrings, bracelets, and other jewelry
A diamond or gemstone with an elongated girdle and tapered ends, a bit like a football.
Special stones used as comparison stones to define a different diamond’s color during the grading process.
Metals are elements that have high luster, malleability, and high melting points, properties that make them desirable for jewelry-making. Gold, silver, platinum, and palladium are among the metals popular for jewelry.
A device for measuring small distances, including the length and width of a gem. Gemologists and jewelers use screw micrometers, dial micrometers, and optical micrometers.
A small unit of measure in the metric system used in the gem and jewelry industries. It is one thousandth of a meter, or approximately 0.03937 inch.
A gem that is cut with two styles, brilliant cut above the girdle and step cut below.
Mohs Hardness Scale
This scale for categorizing minerals according to their level of hardness has been used since the 19th century when it was developed by German mineralogist Fredrich Mohs. Hardness refers to how scratch-resistant a mineral is. The lower the number, the softer the mineral. The softest mineral, a one, is talc, and the hardest mineral, a ten, is diamond.
Used to make many pieces of metal jewelry, a mold is the hollow shape into which a jeweler pours molten metal so that the metal takes on the new shape when hardened.
The part of a piece of jewelry into which a gemstone is secured.
The manufacturer’s suggested retail price is the value placed on an item to be sold, in this case a gem or piece of jewelry. The MSRP is used to set a standard of equal pricing from retailer to retailer. Jewelers set their prices using the MSRP guide.
National Stamping Act
Informally known as the Jeweler’s Liability Act (Gold and Silver Articles), the National Gold and Silver Stamping Act of 1906 was created to protect buyers from fraudulent claims that an item of gold or silver is of a higher quality than it actually is. The act made it illegal for jewelers to stamp gold, silver, or alloys with a mark that falsely indicates that the US government certified the item.
A small spot on the surface of the diamond, typically near the girdle, that remains unpolished. On one hand, a natural is considered to be a blemish, albeit one that doesn’t negatively impact the clarity grade. On the other hand, a natural is an indicator of the cutter’s skill in creating a beautiful polished stone while retaining as much weight as possible.
A very thin inclusion in a diamond or colored gemstone that is noted on a diamond’s plotting diagram and acts as an identifying mark in colored stones.
The Northwest Gemological Laboratories, located near Seattle, WA in the Pacific Northwest of the United States, is a national and international jewelry appraisal service and school. The NGL is a consumer’s advocate and works directly with consumers as well as jewelers.
A small chip or notch on a stone’s surface, usually located on or near the girdle.
Nickel is an elemental metal used as an alloy in jewelry making. When mixed with gold, nickel hardens gold as well as lightens its color. It can be used to replace silver in white gold. Nickel is also important in the annealing process to help create smooth surfaces on the metal produced.
In jewelry making, especially in findings, niobium is used as an alternative to precious metals. Niobium is great for people who are allergic to precious metals because it’s hypoallergenic.
Off Center Culet
When the facet at the bottom of the stone isn’t centered, it negatively impacts the symmetry of the entire stone.
A term used by appraisers when grading the color of a stone, off color is an undesirable description that means that when a stone is viewed top-down through its table, a tint of yellow or other color can be detected. Diamonds can be off-color in varying degrees; the top color rating is actually colorless.
A treatment done to enhance a gem’s color. If a gem has been oiled, it should be disclosed to a buyer.
A description on the transparency scale that ranges in degrees from transparent to translucent to opaque. An opaque stone, such as a common opal, emits no light from within.
Osmium is one of the precious metals and is part of the platinum group metals (PGM). Osmium and platinum alloys are used for standard weights and measures. It is one of the densest known elemental metals.
A brilliant cut diamond that is oval (elliptical) rather than round.
A chemical process involving exposure to oxygen that alters a metal by changing its color or composition. For example, copper becomes tarnished with a green patina when exposed to oxygen.
An elemental metal of the platinum group metals (PGM), Palladium’s softness and silvery white color make it a good metal to alloy with gold to create white gold.
This diamond setting features stones set closely together for a diamond-encrusted effect. Diamond can be secured in different ways for distinct pavé styles.
The measurement of the pavilion, the lower part of a diamond extending from the girdle to the culet. Also known as the culasse.
This pear- or teardrop shape is a hybrid of an oval and marquise shape.
A highly valued gemstone, pearls differ from other gemstones in that they are not mineral but organic. Pearls grow within the soft tissue layers of living mollusks.
Abbreviated “dwt,” the pennyweight is a unit of measurement, a Troy weight, used for weighing precious metals. It is the equivalent of one-twentieth of an ounce.
Per Carat Cost
The price of a diamond divided by its weight (in carats) yields the per carat cost. Price of gems increase as the size increases.
A microscopic, circular, crystal inclusion. Several pinpoints may create a hazy cloud.
Shiny, silver-white, strong, and resistant to corrosion, platinum is a precious metal valued by jewelers. Platinum is used to create beautiful settings for gemstones.
Karat Plumb (KP) is a verification stamped on the inside of a piece of gold jewelry. Karat is the indicator of purity of the gold. Plumb means true or exact. A ring marked 18KP, for example, is guaranteed to be comprised of at least the amount of gold that it should be. KP is a mark of assurance for the gold you are buying.
A unit of measurement created to help jewelers describe and refer to gems by carat. In this simple, 100-point system, a one-carat diamond is a 100-point diamond, and a diamond that is 1/100th of a carat is a one-point diamond.
An instrument that uses polarized light for the purpose of identifying and describing gems.
The light performance and brilliance of a diamond indicated by smoothness and reflectivity of the facets. A skilled craftsman can enhance the flow of light within a diamond as well as light reflectivity. Gems are assigned polish grades from poor to excellent.
A gemstone cut too deeply or too shallowly is considered to be a poor cut stone. Cuts that are the incorrect depth have less brilliance and fire.
Precious metals are metals that are less common than other metals and are considered valuable for their durability, workability, and high luster. Popular precious metals in the jewelry industry include gold, silver, platinum, and palldium.
A square- or rectangular-shaped diamond that has slightly less sparkle than a round brilliant cut. Care is taken by the stonecutter to create the right amount of facets and direct the proper amount of weight toward the pavilion in order to maximize brilliance.
The material used to make the prongs that secure a ring in its setting. Popular prong metals are platinum and white gold because they don’t give a diamond a yellowish color as gold might.
Prong or Claw Setting
A setting that uses four or six prongs to secure a stone. It allows light to enter the stone from every angle, increasing the stone’s brilliance and even making it seem larger than it is.
The relationship between the stone’s dimensions and facet angles, proportion is an important measurement to describe reflected light.
A square brilliant cut with 49 facets, the quadrillion cut is very similar to the princess cut. The quadrillion cut was created and patented by Bez Ambar and is available exclusively through Bez Ambar, Inc.
The radiant cut produces a stone that is square or slightly rectangular in shape and whose corners are cut. With 70 facets in the pavilion and crown, the radiant cut has incredible brilliance and fire, surpassed only by round brilliant cut diamonds.
The process of extracting pure metals from scrap.
Refraction is a principle from physics that refers to the bending of light when it enters an object, such as a diamond or other gemstone. Gem cutters use the principle to manipulate the behavior of light in a stone to create maximum fire.
Rhodium is one of the platinum group metals (PGM). This precious metal is used as a plating finish in the jewelry industry, often to enhance the white color in white gold.
Ring Adjuster/Ring Guard
Used to adjust the size of a ring, either to reduce the size without cutting and soldering it or to help slip a tight ring over a knuckle.
The ring itself prior to the mounting of a gemstone.
The numerical description of the ring. Ring size takes into consideration the diameter of the wearer’s finger as well as the knuckle.
A girdle whose surface is irregular, granulated, pitted, and even chipped.
A gemstone whose final shape is circular. The round brilliant cut, with 57 facets, is the most popular diamond shape/cut.
A precious metal in the platinum group metals (PGM). Ruthenium is white or grayish white and is used in the jewelry industry to harden platinum.
A ring or other jewelry finish that is smooth to the touch and appears matte rather than bright and shiny.
Saturation refers to the brightness and intensity of a stone’s color and relates to wavelength and intensity of a color on the spectrum of light. Diamonds and other gems are rated on a saturation scale ranging from neutral to vivid.
Along with brilliance and fire, scintillation is the third consideration regarding a diamond’s light performance. Movement of the diamond under a light creates varying intensities of light to reflect off of the stone’s facets creates scintillation, which many people refer to as sparkle.
Jewelry-shop waste such as precious metal cuttings large enough to be sorted for refining.
A ring setting that has mounted side stones and an empty set of prongs. The center stone is selected separately and then mounted in the setting.
A category of gemstones that includes all colored gemstones other than the four which are considered precious (diamond, ruby, sapphire, and emerald). Differences in softness, brilliance, and rarity separate the precious stones from the semi-precious. The American Gem Trade Association (AGTA) no longer uses the terms precious and semi-precious.
The setting holds the center gemstone securely in place while adding unique style to the ring. Numerous different setting styles exist.
Many different metals can be used in a ring’s setting. Sometimes, the metal of the ring is the same as the metal used in the head, basket, and prongs. Other times, the metals are different. Common precious metals used in setting are platinum, gold (white, yellow, or rose), palladium, and titanium.
A shallow cut is undesirable because the angles and proportions are wrong. The pavilion isn’t deep enough in a shallow cut stone, resulting in reduced brilliance.
Also called the band, the shank is the part of the ring that fits onto the finger.
The shape is the form or contour of the stone, such as round, oval, square, heart, and more. Shape is different than cut, which is how a gem cutter crafts a rough stone into a polished one.
SI 1/SI 2 (Slightly Included)
Two of the 11 clarity grades on the GIA International Diamond Grading System scale. Slightly included stones contain inclusions that a skilled grader can detect under 10x magnification. Along with very slightly included (VS), SI gems are the most common.
A stone belonging to a group of stones in a setting that enhances the center stone.
A precious metal used in jewelry making. Silver is softer than gold, which makes it less durable but also more affordable than gold or white gold (an alloyed gold that looks like silver).
A simple cut, round in shape, containing only 16 or 17 facets (as opposed to the 57 or 58 facets of a round brilliant cut). Single cuts are used for small gemstones, often those used in settings containing numerous close-set stones.
In gemology, an instrument used to measure light properties.
Symmetry is a description of facet shape and arrangement as well as the stone’s contour and alignment. It affects the gem’s light quality and interaction, thus affecting brilliance, fire, and scintillation. Symmetry is graded on a scale with values of Ideal, Excellent, Very Good, Good, Fair, or Poor.
Table spread, or table percentage, is a measurement expressing how the diameter of the table facet compares to the diameter of the whole stone. The ideal range of the table spread/percentage is between 53% and 60% of the width of the stone’s outline.
The largest facet of a gemstone, the table is the flat surface at the top of the stone. It allows light to escape from within and therefore is an important factor in brilliance and fire. For maximum beauty, performance, and value, the table must be neither too big nor too small but in proper proportion to the rest of the stone.
Gradually heating precious metals in order to harden them.
A stone setting that secures the stone between the “ends” of the ring rather than within prongs and a basket.
A strong, light metal that is light-gray in color, titanium is often used in the jewelry industry for multiple reasons. It is hard yet lightweight, so it is durable, scratch- and bend resistant, and comfortable to wear. Titanium is fully hypoallergenic and thus is a good replacement for nickel and other metals that cause allergic reactions.
An expression of a stone’s color intensity. Tone is described on a scale from light to dark.
Total Weight/Carat Total Weight
This is a measure of the combined weight of all stones in a setting.
A legal registry with the US Patent Office that protects an asset, such as a business or product. Trademarks are the mark of a manufacturer, importer, wholesaler, or retailer.
Trillion Shape/Trilliant Cut
Trilliants are brilliant fancy cut stones that are triangular in shape. Trilliants are often used as side stones.
Dating back to the middle ages, the Troy ounce is a unit used in measuring weight of precious metals. The Troy ounce is used in pricing precious metals such as gold, platinum, and silver. Gold prices are expressed in ounces, which are actually Troy ounces rather than standard ounces. A Troy ounce is equal to 31.1034768 grams. There are 14.58 Troy ounces in one pound.
An inclusion that appears flat, irregular, and ribbon-like and radiates outward from the stone’s center.
A device used to clean jewelry in which a solution containing a cleansing agent is vibrated at frequencies too high to be detected by the human ear. The vibrations dislodge dirt and other particles from the setting.
A prong setting that wraps around the point of a fancy shaped stone in order to protect all of the fragile points of the stone.
Very Good Cut
A grading of the quality of a stone’s cut. The GIA Cut Grading System rates quality on a scale with ranks of Excellent, Very Good, Good, Fair, and Poor. Cut is analyzed for brilliance, fire, scintillation, weight ratio, durability, polish, and symmetry. A Very Good Cut diamond properly reflects most of the light entering the stone and has superior fire and brilliance.
Vickers Hardness Test
A method of testing the hardness of a metal by pressing a diamond pyramid into the metal with increasing force, from five to 120 kilograms.
VS 1/ VS 2 (Very Slightly Included)
Two of the 11 clarity grades on the GIA International Diamond Grading System scale. VS 1 and VS 2 graded stones contain small inclusions that a skilled grader can spot, sometimes fairly easily but sometimes with difficulty, under 10x magnification.
VVS 1/VVS 2 (Very, Very Slightly Included)
Two of the 11 clarity grades on the GIA International Diamond Grading System scale. These gemstones contain such minor inclusions that they are difficult for even a skilled grader to detect under 10x magnification.
A tool used for casting in jewelry making. Wax injectors pressure-force molten wax into a mold to create a pattern.
Well cut diamonds and colored gemstones are cut with proportions that maximize light performance to create stunning brilliance, fire, and scintillation.
White diamonds can be confused with colorless diamonds, those diamonds that are graded on the official GIA color scale and prized for their degree of colorlessness. White diamonds have a color, and that color is white—the sum of all colors. The white color comes from sub-microscopic inclusions that scatter the light passing through the stone.
Gold in its pure form (24 Karat) is yellow, but it must be strengthened to be used in jewelry. To strengthen gold while retaining its yellow hue, it’s alloyed with metals like copper, silver, zinc, and more.
An alloy metal sometimes used in jewelry making.