Below is a list of terms are commonly found on diamond certificates.
| Term |
Definition |
| 4C's |
4 criteria used for diamond grading and certification |
| 5th C |
Refers to the diamond certificate |
| Colored Diamonds |
The world's diamonds can be divided into two color groups. Most of the diamonds range from white to deep yellow - which includes yellowish hues of white. The second group include a variety of hues (such as red or black) known as "Fancy Colors". |
| Conflict Diamonds |
These are illegal diamonds mined in a war zone and sold to finance an insurgency, invading army's war efforts, or a warlord's activity. They are also known as blood diamonds, converted diamonds, hot diamonds, or war diamonds |
| Defects in Diamonds |
Imperfections in the crystal lattice of a diamond affect its material properties and determine to which type a diamond is assigned. See also diamond clarity scale |
| Diamond Blemish |
External features, confined to a gemstone's surface. |
| Diamond Carat |
The weight of the diamond. 1 carat = 0.2 grams |
| Diamond Certificate Number |
The serial number of the diamond or gemstone for which the certificate is issued. |
| Diamond Clarity |
Indicates how "pure" the diamond is, meaning whether it has any blemishes or inclusions. |
| Diamond Clarity Scale |
Diamond clarity scale is as follows:
FL = Flawless - completely
IF = Internally flawless. Flaws are only present externally and can be removed by further polishing the stone.
VVS1 - VVS2 = Only an expert can see flaws using a 10X microscope. When an expert can see the flaws by looking from the top of the diamond, it is a VVS2. If an expert can only detect flaws when looking from the bottom of the stone, then it is a VVS1.
VS1 - VS2 = Flaws are not easily visible with a 10X microscope - it takes more than10 minutes.
SI1 - SI2 = Flaws are visible with a 10X microscope
I1 - I3 = Flaws are visible on the diamond with the naked eye. |
| Diamond Cleaning |
Methods implemented to remove oils and dirt from your diamond to keep it sparkling. |
| Diamond Color |
Diamond color is graded on a scale of D-Z and indicates how colorless or "white" the diamond is. The closer to D the diamond, the more colorless it is and more valuable.
Diamond color may result from:
1) The chemical composition of the diamond
2) External substances found within the stone
3) Optical characteristics that affect the way the light penetrates the diamond |
| Diamond Crown |
The facet above the girdle. |
| Diamond Culet |
A tiny flat facet that cutters sometimes add at the bottom of a diamond's pavilion to protect the tip. |
| Diamond Cut |
Describes the outline or shape of the diamond such as: round brilliant, emerald cut, pear, oval, princess cut. |
| Diamond Facet |
A smooth surface of the diamond. |
| Diamond Finish |
Grades the polish and symmetry of the diamond. |
| Diamond Fluorescence |
A glow which emanates from certain diamonds when exposed to ultraviolet light caused by trace amounts of Boron in the diamond. |
| Diamond Girdle |
The widest part of the diamond. |
| Diamond Inclusion |
Features enclosed within a gemstone or extends into it from the surface. |
| Diamond Measurement |
Length, width and depth of the diamond in millimeters. |
| Diamond Pavilion |
The facet below the girdle. |
| Diamond Polish |
Refers to how smooth the surface of the diamond is and whether marks remain from the polishing process. |
| Diamond Proportion |
The size of the various facets and the angles at which they lie relative to each other. |
| Diamond Shapes |
Diamonds are available in a variety of shapes also referred to as cut. |
| Diamond Sizes |
Diamond size is usually measured by Carat (weight). |
| Diamond Symmetry |
Refers to how accurately opposing facets have been placed and shaped, they should be a mirror image of each other. |
| Diamond Treatments |
Processes which enhance a diamond's appearance. There are five different types of treatments: Fracture Filling, Irradiation, Laser Drilling, Surface Coating, High Pressure - High Temperature (HPHT). |
| Diamonds |
An allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. |
| Fracture Filling |
A process using a glass formula to fill in fractured diamonds to conceal flaws. |
| Gemological Lab |
Laboratories with staff and equipment that specialize in identifying and grading gemstones. |
| Gemology |
A branch of mineralogy that deals with identifying and grading natural and artificial gemstones. |
| Hearts & Arrows |
Round brilliant diamonds are cut in a specific way so that when it is examined by an H&A viewer from the bottom of the diamond, eight hearts are displayed through the pavillion. When viewed from the top of the diamond eight arrows are visible through the crown. When a diamond has Hearts & Arrows, it is considered a high quality cut diamond and is therefore more valuable. |
| High-Pressure, High-Temperature (HPHT) |
This treatment method uses heat to change the color of naturally brown diamonds to white. |
| Industrial Diamonds |
Diamonds that are considered lower quality. For that reason they are used for industrial purposes. |
| Irradiation |
A process used to change or enhance the color of a diamond. |
| Laser Drilling |
A technique used to remove crystal or iron oxide inclusions. This helps to enhance the clarity of a diamond. |
| Mazal & Bracha |
Traditional phrase used by the diamond industry when closing a deal.
Mazal = Luck and Bracha = Blessing |
| Polished Diamonds |
Term for diamonds that have undergone processing unrelated to size, shape or any other feature. |
| Surface Coating |
This is a technique to enhance the color of a diamond. One of the oldest treatment methods using foil backings to cover the diamond with a color. Today there are other ways of doing this which includes the application of dyes and films. |
| Synthetic Diamonds |
Artificial or man made diamonds that possess the same atomic structure, chemical composition and physical properties of real diamonds. |
See EGL International's Online Interactive Diamond Certificate Glossary below.