Diamond Glossary | Diamond Brain

The Ultimate Diamond Glossary

AGS: Stands for American Gen Society, established in the year 1934. AGS is known for grading loose diamonds, and it also gives grading reports and certificates.

Angular Spectrum Evaluation Tool ( ASET): A viewing device that color-codes the angles though which a diamond gathers light. Developed and created by AGS.

Artisanal Mining: Small scale mining done by individuals with the help of a single hand tools.

Bezel-setting: A special type of setting where diamonds are secured with a thin metal strip along: its perimeter.

Blemish: An absolute term that is used to describe external marks on a diamond’s surface like nicks, scratches, abrasions and extra facets.

Brightness: Refers to the amount of white light that diamond emits.

Brilliance: Brilliance refers to the dazzle that diamond gives out when white light passes through it. Diamonds that give out a large amount of light can be called brilliant, depending on the contrast of the facets.

Brilliant-cut: A special type of facet arrangement, where all the facets look like appearing from the center to the outer edges. This is known to be a brilliant cut because it maximizes the brilliance factor of a diamond. Common shapes of this cut include princesses, round, hearts, marquises and pears.

Carat: Refers to the standard unit of measurement for diamonds. One carat is equivalent to 0.2gms and derives its name from ‘carob bean’, once the standard unit of measurement for gemstones.

Carbon Spots: A term used inaccurately in the jewelry business to describe certain kinds of inclusions, especially those crystals that have a dark appearance. These spots are different because that don’t resemble the white shine of general crystals. Mostly viewable under the microscope, these spots make no difference to the brilliance.

Cavity: A special type of inclusion in the diamond that has a deep or large opening.

Clarity: It refers to the degree to which a diamond is free from various kinds of inclusions. The grading scale starts from FL(flawless) to imperfect.

Clarity Enhancement: The processes that improve the clarity of a diamond. In general, it may mean filling fractions with glass.

Cleavage: Refers to the tendency of diamonds or other crystalline materials to split in one (or more directions) in parallel to its crystallographic planes. It is one of the complicated processes used to cut diamonds for creating shapes.

Clouds: Group of tiny white inclusions inside a diamond that look like clustered cloud. These inclusions are so small that one inclusion cannot be distinguished from the other, even under the microscope. Clouds are not visible with the naked eye and hardly make any impact on the clarity grade.

Color Grading: Refers to systematic way of grading diamonds according to their colorlessness. This may also include grading on the basis of spectral hue, color depth and purity. Generally, white diamonds are graded between D (fully colorless) to Z (yellow tinted diamonds) by AGS and GIA.

Crown: Refers to the upper portion of a diamond that lies above the girdle. There is table facet in the crown that is generally surrounded bezel and star facets (found in round and fancy cut) or concentric facets that reach the girdle from the table (found in emerald cuts).

Crown Angle: The measure of the angle between the bezel facets and the girdle plane. It helps to find the amount of dispersion and the table size.

Crown Height: Refers to the height of the diamond that is above the girdle.

Crystal: Refers to mineral deposit often found trapped in the diamond.

Culet: Refers to the smallest facet that is added to the bottom of a full cut diamond to protect and safeguard the tip of the pavilion from being damaged. Large culets were once used extensively in the early part of the century like Old Mine Cut or Old European Cut. Presently, most diamonds do not have culets or have extremely small ones.

Cut: The cut of a diamond refers to finish and proportions of a fully cut diamond. It’s a complete manmade contribution to the beauty of a diamond.

Depth: The distance between the table and culet, generally measured in millimeters.

Depth Percentage: It can be defined as the depth of the diamond at odds with the average width. The depth percentage of a diamond is extremely crucial for its value and brilliance.

Diamond: An allotrope of carbon in which carbon atoms are arranged in a cubic, isometric, or crystal arrangement. Diamond is known to have a unique arrangement of carbon, which is the main reason behind its dazzle and beauty.

Dispersion: The facets of diamonds are cut in a way that it disperses white light into many colors. This particular appearance as small flashes of color across the diamond when tilted is known as dispersion, or often called ‘fire’. Dispersion may differ in colored and fancy diamonds.

EGL: Stands for European Gemological Laboratory, which grades diamonds and shells diamond certificates.

Emerald Cut: Generally refers to square and rectangular shaped diamonds. Emerald cut diamonds has three concentric rows of facets around the table and around the culet. The cut is also known as ‘step cut’ as it has flat, broad planes that look like stair steps.

Eye-Clean: While checking the clarity factor, a diamond that has no blemishes, inclusions visible to the naked human eye are called eye-clean diamonds.

Facet: The smooth and polished planes on the surface of the diamond. These facets allow light to pass through the diamond and reflect from its surface, to create the beautiful play of light and color. A round diamond is called brilliant if it has 58 facets (including the culet).

Feather: refers to fracture within a diamond that resembles like a white feather. Diamonds go through tremendous pressure during their natural making process, which often gives out these fractures. In general, fractures have no effect on the diamond’s stability, provided adequate care is taken in customary use. Although, one might think of these diamonds as imperfect, these can still last for a lifetime with regular care.

Finish: The qualities that a diamond cutter or craftsman impart to a diamond is called the finish. A ‘finished’ diamond id the one that has gone through all processes and is ready to be sold. “Finish” is graded in two different categories namely polish and symmetry.

Fire: The rainbow of colors that is seen when light disperses through a diamond.

Fluorescence: This is an exceptional property of diamond and other gemstones to glow in ultra violet light and similar wave lengths of light. Although diamonds depict this property in all kinds of light, it is advised to avoid blue. Diamonds appear to be milky in unusually strong florescence.

Fracture: Any break or crack in a diamond that is not in the direction of the plane. Fractures occur acutely irregularly on the surface and inside the diamond.

Fracture Filling: The process by which cranks and cavities in a diamond are filled with other artificial substances.

GIA: Stands for Gemological Institute of America.

Girdle: Refers to the outer edge of the diamond that surrounds it from all sides. Girdle can be either faceted or polished or unpolished. Girdle is explained by the appearance at the thinnest and thickest point, and it is not graded.

Grading Report: Refers to the report issued by diamond grading laboratories describing the various features like weight, color, proportions, polish, etc for a particular diamond. GIA and AGS are known to have consistent and reliable grading systems. Although, it is wise to remember that labs never certify diamonds but just grade them.

Heart-shape Cut: A popular fancy cut shape of diamond often gifted as a token of love.

IGI: Stands for International Gemological Institute, a laboratory that grades diamonds and gives written appraisal reports.

Inclusion: Any kind of natural imperfections within a diamond like feathers, needles, clouds, crystals and pinpoints.

Laser Drill Hole: A remarkably small and tiny tube created in a diamond by the process of leather drilling for treating it for other things. Generally crystals are removed by this technique where a hole is drilled, and acids are put into the same, which dissolves the crystal. This, in turn, improves the quality and clarity of the diamond.

Laser Drilling: The process of making a hole using laser drill technique to enhance the quality of a diamond.

Length-To-Width Ratio: Refers to the comparison of width and length of the diamond’s girdle. The ratio is calculated by dividing the length of the girdle by the width. There are some lengths to width ratios that are considered to be more appealing. General ‘considered’ proper ratios are heart 0.98-1.02, Pear 1.50-1.75, oval 1.33-1.66 and emerald 1.50-1.75.

Loupe: A clear and small magnifying glass that is used to examine diamonds and other gemstones. A standard magnification is assumed to be 10x.

Mine Cut Diamond: An extremely old and early form of diamond that featured a square-shaped girdle, small table and deep pavilion and a remarkably large culet.

MOHS Scale: ten point scale that is used to measure mineral hardness. Diamond has a score of 10.

Marquise Cut: A fancy shaped diamond elongated with points at every end.

Natural: These are small parts of the original diamond’s rough surface that are left on a polished diamond, generally close or on the girdle. The presence of natural is considered to be the skill of the cutter to polish a diamond competently without compromising on the weight. Naturals are often so fine that they hardly affect the clarity and are not visible to the naked eye.

Oval Cut: a particular fancy cut diamond, which looks like an elongated version of the traditional round cut.

Pavilion: Refers to the portion of a diamond below the girdle.

Pavilion Angle: The measure of the angle between the girdle and the main facet of the pavilion.

Phosphorescence: The light that is emitted from diamond or similar gemstones after the light or energy source is removed.

Pinpoints: Remarkably small inclusions in diamonds

Point: A unit for measuring weight of diamonds. One point is equal/equivalent to one-hundredth of a carat.

Polish: Any blemish on the surface of diamond that doesn’t affect its clarity. Grades of polishes range between poor to excellent.

Princess Cut: A peculiar fancy shape of diamond generally of square and rectangular type.

Radiant Cut: A brilliant cut shape that looks like a rectangle or square but with the corners cut off.

Ratio: A simple comparison as how long is a diamond than it is wide. Round diamonds are never measured with ratio as it is intended for fancy shaped diamonds only. There are no general standards, but the ratio is dependent on personal choice.

Scintillation: Refers to tiny flashes of light that is visible on moving the head. In simple terms, it can be called as the sparkle of a diamond.

Shape: Diamonds are generally cut into forms known as shapes of diamond. Round is the traditional and popular shape, while fancy shapes include emerald, marquise, pear, oval, heart, princess, and trillion.

Single-cut: refers to extremely small diamonds having 16 or 17 facets unlike 57 or 58 facets of fully cut diamond. Small single cut diamonds are generally used in clusters or groups or are used for pave jewelry.

Step Cut: It is one of the three styles for arrangements of facets. There are three concentric rounds of facets arranged specially around the table and three more concentric rounds on the pavilion, around the culet. The other two facet arrangement styles are brilliance cut and mixed cut.

Symmetry: It refers to variations in the symmetry of the diamond. This may refer to certain variations along the symmetry like non-pointing facets or misalignment of facets. It is often used as an indicator of quality for a diamond and is graded between ideal to poor.

Table: This refers to the largest facet on the top of the diamond, which allows maximum light to pass through the diamond.

Table Percentage: Refers to the width of a table divided by the diamond’s average diameter.

Trilliant Cut: A special type of fancy cut diamond that is triangular in shape.