Helping our customer’s buy a diamond is the heart of our mission. Windy City Diamonds is a family owned and operated business that began with the entry of the Zimmerman’s grandfather into the jewelry business in 1929. With multi generational relations in the diamond business, we buy each stone one at a time. There will never be “Program” diamond merchandising with average grading and pricing, and signed contracts require our suppliers to provide only conflict free diamonds. Our greatest honor is receiving a referral from a valued friend and guiding a new Windy City Diamond guest through their first diamond buying process.
We exclusively refer to and use the Gemological Institute of America’s diamond grading system. Our diamond center stones of one carat and greater have GIA Diamond Grading Reports, which are the most trusted in our industry. These reports, also called certificates, are critical to us and will help establish authenticity and value in the future. The details on each GIA Diamond Grading Report will also help to identify each individual diamond in the future. Most insurance companies require a copy of this GIA report, along with a current appraisal to add a diamond to their insured’s insurance schedule.
Beautiful. Rare. Cherished. Each diamond is unique and is a miracle of time, place and change. And each has specific qualities that establish its value.
Until the middle of the twentieth century, there was no agreed-upon standard by which diamonds could be judged. GIA created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut and Carat Weight. Today, the 4Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world. The creation of the Diamond 4Cs meant two very important things: diamond quality could be communicated in a universal language, and diamond customers could now know exactly what they were about to purchase.
As creator of the Diamond 4Cs and the International Diamond Grading System™, GIA is not only a global authority, but the world’s trusted source for unbiased assessment.
The shape of the diamond is often confused with the cut. Choose the shape that you like based on your style and you cannot go wrong.
Learn More About Popular Shapes
The cut of a diamond determines its brilliance or sparkle. Each shape will be cut differently. Before a diamond is cut, the location of inclusions and flaws, the natural coloration, and the original shape of the rough stone are studied extensively. The stone facets are then mapped out and cut in a way that maximizes size, shape, and clarity. For optimal light performance, you will want a diamond that is cut neither too shallow nor too deep.
A diamond’s cut is crucial to the stone’s final beauty and value. And 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 desirable visual effects such as:
Brightness: Internal and external white light reflected from a diamond
Fire: The scattering of white light into all the colors of the rainbow
Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond
The width and depth have the greatest effect on how light travels within the diamond, and how it exits in the form of brilliance.
Too Shallow: Light is lost out the bottom causing the diamond to lose brilliance.
Too Deep: Light escapes out the sides causing the diamond to appear dark and dull.
Cut Determines Brilliance
The diamond’s proportions, specifically the depth compared to the diameter, and the diameter of the table compared to the diameter of the diamond, determine how well light will reflect and refract within the diamond.
Diameter: The width of the diamond as measured through the girdle.
Table: The largest facet of a gemstone.
Crown: The top portion of a diamond extending from the girdle to the table.
Girdle: The narrow band around the widest part of a diamond.
Pavilion: The bottom portion of a diamond, extending from the girdle to the culet.
Culet: The facet at the tip of a gemstone. The preferred culet is not visible with the unaided eye (graded “small” or “none”).
Depth: The height of a gemstone measured from the culet to the table.
Polish and Symmetry Affect Sparkle
Polish and symmetry are two important aspects of the cutting process. The polish grade describes the smoothness of the diamond’s facets, and the symmetry grade refers to alignment of the facets. With poor polish, the surface of a facet can be dulled, and may create blurred or dulled sparkle. With poor symmetry, light can be misdirected as it enters and exits the diamond. The polish and symmetry grades are clearly listed in each diamond detail page and within the AGSL or GIA diamond grading report. For the most beautiful diamond, look for a symmetry grade of ideal (ID), excellent (EX), very good (VG), or good (G) for an AGSL graded diamond, and excellent (EX), very good (VG), or good (G) for a GIA graded diamond. Avoid diamonds with symmetry grades of fair (F) or poor (P), as the alignment of their facets may misdirect light so severely that it affects the brilliance of the diamond.
Diamond measurements are calculated and applied to a cut grading scale that makes it easy to understand how well each reflect light:
Which Cut Grade is Best?
- For the best value in a brilliant diamond, choose a diamond with a cut grade of good or very good, and polish and symmetry grades of very good or good.
- In an ideal- or very-good cut diamond with very good or good polish and symmetry, consider less expensive grades of color and clarity — look for a diamond with G or H color and SI1 or SI2 clarity.
Diamonds are graded based on the amount of color they do or do not possess. The scale runs from D (colorless) to Z (light yellow). An absolutely colorless diamond is rare and therefore very valuable.
The diamond color evaluation of most gem-quality diamonds is based on the absence of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and consequently, a higher value. GIA’s D-to-Z diamond 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.
Many of these diamond 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.
A diamond is distinguished by its natural characteristics, just as a person would be noted for her blue eyes or his brown hair. Notated as a diamond's clarity, these characteristics can be present on the surface (blemishes) or within the stone (inclusions). The clarity is judged by the number and types of these characteristics and is designated using a scale that runs from Fl, defined as flawless, to I3, defined as inclusions visible with the naked eye. A flawless diamond is truly rare.
The GIA Diamond 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
The unit of measure used for the weight of a diamond is the carat. As a matter of reference, a carat is equivalent to .2 grams or .007 of an ounce. Carat weight can also be divided further by using points. There are 100 points in one carat. So a 1/4 (.25) carat stone can also be expressed as 25 points and mean exactly the same thing. When comparing two diamonds, please note that just because one is twice the carat weight of the other does not mean that it will appear to be twice the size.
Diamond carat weight is the measurement of how much a diamond weighs. A metric “carat” is defined as 200 milligrams.
Each carat can be 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.’