Diamond Glossary

The knowledge and more information you have the better diamond purchase you will make. Here are a number of diamond terms that are used by jewelers to describe diamonds and which appear on diamond grading reports.

D:

Depth:
The height of a diamond from the culet to the table. The depth is measured in millimeters.

Depth Percentage:
On a diamond grading report, you will see two different measurements of the diamond's depth-the actual depth in millimeters (under "measurements" at the top of the report) and the depth percentage, which expresses how deep the diamond is in comparison to how wide it is. This depth percentage of a diamond is important to its brilliance and value, but it only tells part of the story. Where that depth lies is equally important to the diamond's beauty; specifically, the pavilion should be just deep enough to allow light to bounce around inside the diamond and be reflecting out to the eye at the proper angle. Keep in mind, also, that a depth percentage that might be excessive for one diamond cut might be necessary for another type of cut. For example, a 75% or 78% depth in a princess cut diamond would be typical and quite attractive. However, a depth of even 65% would be unnecessary and even detrimental to a round diamond's beauty.

Diamond:
A crystal made up of 99.95% pure carbon atoms arranged in an isometric, or cubic, crystal arrangement. It is this unique arrangement of the carbon atoms that makes diamond look and behave differently from other pure carbon minerals such as graphite (the soft black material used to make pencils).

Diamond Cutting:
The method by which a rough diamond that has been mined from the earth is shaped into a finished, faceted stone. As a first step, cleaving or sawing is often used to separate the rough into smaller, more workable pieces that will each eventually become an individual polished gem. Next, bruting grinds away the edges, providing the outline shape (for example, heart, oval or round) for the gem. Faceting is done in two steps: during blocking, the table, culet, bezel and pavilion main facets are cut; afterward, the star, upper girdle and lower girdle facets are added. Once the fully faceted diamond has been inspected and improved, it is boiled in hydrochloric and sulfuric acids to remove dust and oil. The diamond is then considered a finished, polished gem.

Diamond Gauge:
An instrument that is used to measure a diamond's length, width and depth in millimeters.

Dispersion:
Arranged around the table facet on the crown are several smaller facets (bezel and star facets) angled downward at varying degrees. These facets, and the angles at which they are cut, have been skillfully designed to break up white light as it hits the surface, separating it into its component spectral colors (for example, red, blue and green). This effect, which appears as a play of small flashes of color across the surface of the diamond as it is tilted, is what we refer to as the diamond's dispersion (also called "fire"). This play of color should not be confused with a diamond's natural body color (normally white, though sometimes yellow, brown, pink or blue in the case of fancy color diamonds) which is uniform throughout the entire diamond and is constant, regardless of whether it is being tilted or not.

Diamond Dossier/ Laser Inscribed:
This is a new program offered by the GIA in grading standards, with a laser inscribed girdle and we recommend it highly. This gets the diamond inscribed and entered into the registry, for an added level of security and protection. This program is for diamonds of less than a carat size.

Deep cut:
Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. When a diamond is cut too deep, it will lose or leak light through the side or bottom. This results in less brilliance and value. Click here to learn more about deep cut.

Diamond Grading Reports:
There are many recognized gemological laboratories that can grade your diamond for a fee. Click here to find more information on diamond grading reports.

De Beers Consolidated Mines:
This company is the major factor in the diamond industry, because it holds a controlling interest in a number of diamond-mining companies and in companies having buying contracts with independent producers. It owns or controls all of the important pipe mines in South Africa and Consolidated Diamond Mines of South-West Africa, Ltd. Williamson Diamonds, in Tanzania, is owned by De Beers and the government of that country on an equal basis.

Diamantiferous:
Diamond-bearing ground.

Diamond Cutter:
Any workman engaged in the cutting and polishing of diamonds. One who rounds up rough diamonds as a step in the fashioning of brilliants.

Diamond Saw:
A saw used for dividing or separating diamonds. A diamond-charged blade used as a cutting edge in fashioning colored stones or in various applications in industry.

Diamond Syndicate:
In the early days of South African diamond fields, the word “syndicate” was used to refer to various groups of individuals and companies that held controlling interests in diamond production and distribution. In 1890, a syndicate consisting of ten firms offered to produce all of De Beers Company’s diamonds. This seems to have been the embryo of the famous diamond syndicate that became so well known to jewelers in the early part of the 20th century as the price-fixing and market-controlling factor of the diamond industry. In various forms, a diamond syndicate composed of different persons or firms functioned in this capacity, until the crisis of 1929 demanded a marketing organization of a more rigid kind with greater capital. Although the term syndicate is no longer meaningful, it is often applied to De Beers Consolidated Mines, Ltd., because it holds a controlling interesting in a number of diamond-mining companies and in companies that have buying contract with independent producers, including the Diamond Corporation, Ltd.

Diamond Trading Co., Ltd:
The organization that markets to the diamond industry the gem diamond it buys from the Diamond Purchasing & Trading Co., Ltd.

Dodecahedron:
One of the seven basic forms in the highest symmetry (“hexoctahedral”) class of the cubic, or isometric, crystal system. It has 12 rhomb-shaped faces, each of which intersects two of the crystallographic axes and is parallel to the third. This form is uncommon in gem diamonds.

Draw Color:
When several diamonds are placed together in a diamond paper and light passes through one stone after another, each stone tends to intensify the slight color of the other. The group of stones is then said to draw color. The term is also used to describe an individual diamond with a visible body color.

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