Diamond Education

Cut is one of the most important factors to consider

A diamond’s cut grade is really about how well the facets interact with light, whether its round, heart-shaped, marquise, or pear. Diamonds are renowned for their ability to transmit light and sparkle so intensely.

Precise artistry and workmanship are required to fashion a stone so that its proportions, symmetry, and polish deliver the magnificent return of light only possible in a diamond. The cut is measured using the GIA’s international grading system in which cut grades range from Excellent to Poor. A diamond’s cut is crucial to the stone’s final beauty and value. Of all the diamond 4Cs, it is the most complex and technically difficult to analyze.

To determine the cut grade of the standard round brilliant diamond – the shape that dominates the majority of diamond jewelry – GIA calculates the proportions of those facets that influence the diamond’s face-up appearance. These proportions allow GIA to evaluate how successfully a diamond interacts with light to create the three desirable visual effects such as

• Brilliance: Internal and external white light reflected from a diamond
• Fire: Internal and external white light reflected from a diamond
• Scintillation: The amount os sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond

GIA’s diamond cut grade also takes into account the design and craftsmanship of the diamond, including its weight relative to its diameter, its girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.

Note: Only round brilliant cut diamonds in the D to Z color range get a cut grade from GIA while all the other shapes do not have a cut grade.

Derco only sells and recommends excellent cut to good cut grades because they will maximise the sparkle and shine.

Understanding Color

Second to cut, a diamond’s color is the second most important factor to consider, as it can be noticeable to the naked eye.A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. While many diamonds appear to be colorless most contain tints of yellow, brown or grey tint in varying degrees. GIA’s D-to-Z color-grading system measures the degree of colorlessness by comparing a stone under controlled lighting and precise viewing conditions to masterstones of established color value.The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z. Many of these color distinctions are so subtle that they are invisible to the untrained eye; however, these distinctions make a very big difference in diamond quality and price.

How is a Diamond’s Color Graded?

Choosing the right color.

We recommend any color from D to J.The most popular color grades purchased by our clients at Derco are in the F to I color range.

A Diamond’s Clarity

Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal characteristics called ‘inclusions’ and external characteristics called ‘blemishes.’

Evaluating diamond clarity involves determining the number, size, relief, nature and position of these characteristics, as well as how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value.

The GIA Clarity Scale has 6 categories, some of which are divided for a total of 11 specific grades.

• Flawless (FL) No inclusions and no blemishes visible under 10x magnification
• Internally Flawless (IF)No inclusions visible under 10x magnification
• Very, Very Slightly Included (VVS1 and VVS2) Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
• Very Slightly Included (VS1 and VS2)Inclusions are observed with effort under 10x magnification, but can be characterized as minor
• Slightly Included (SI1 and SI2) Inclusions are noticeable under 10x magnification
• Included (I1, I2, and I3) Inclusions are obvious under 10x magnification which may affect transparency and brilliance

Choosing The Right Clarity

While flawless diamonds are the rarest and most highly prized, a diamond does not have to be flawless to be striking. In fact, the most popular clarity ranges are the VS1-SI1.Diamonds in these clarity ranges can appear flawless and eye-clean to the naked eye.Some SI2 diamonds might also be eye-clean.

Note: For Asscher and Emerald cut diamonds we recommend a VS1 or higher clarity grade.

What Is Carat Weight

To put it simply, diamond carat weight measures how much a diamond weighs.

A metric “carat” is defined as 200 milligrams. Each carat is subdivided into 100 ‘points.’ This allows very precise measurements to the hundredth decimal place. A jeweler may describe the weight of a diamond below one carat by its ‘points’ alone. For instance, the jeweler may refer to a diamond that weighs 0.25 carats as a ‘twenty-five pointer.’ Diamond weights greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as ‘one point oh eight carats.One should not forget that high carat weight does not necessarily mean a larger looking diamond, since the weight distribution is also affected by the quality of the cut.

All else being equal, diamond price increases with carat weight, because larger diamonds are more rare and more desirable. But two diamonds of equal carat weight can have very different values (and prices) depending on three other factors within the 4Cs: Clarity, Color, and Cut.

What is fluorescence

Fluorescence is the visible light some diamonds emit when they are exposed to invisible ultraviolet (UV) rays. On a GIA diamond grading report, fluorescence refers to the strength, or intensity, of the diamond’s reaction to long-wave UV, which is an essential component of daylight. The light emitted lasts as long as the diamond is exposed to the ultraviolet source. The majority of diamonds with medium blue, string blue or very strong blue fluorescence appear cloudy and milky. Because of this, these diamonds sell for 25 to 35 percent less than similar diamonds with faint or no fluorescence.

GIA Diamond Grading Report

The GIA Diamond Grading Report includes an assessment of the 4Cs – Color, Clarity, Cut, and Carat Weight – along with a plotted diagram of its clarity characteristics and a graphic representation of the diamond’s proportions. GIA issues the Diamond Grading Report for loose natural diamonds only, weighing 0.15 carats or more. For standard round brilliant cut diamonds falling in the D-to-Z color range, the report also includes a GIA Cut grade.