Loose Diamonds and the Laboratory
The Gemological Institute of America aims to be as precise as possible when it comes to certified diamonds. Jewels are placed in uniform packaging before arriving at the laboratory to reduce factors that may skew the grading process. The stones are then evaluated by professionals under controlled lighting. Another step to get accurate grading is by ensuring that the diamond is loose, or outside of a setting.
If a diamond is examined while it’s still mounted, it’s harder to gauge its carat size. Weighing a piece of jewelry instead of individual loose diamonds will skew the result towards a higher carat. While carat may be estimated by measuring the length, width and depth of a jewel, this is not as accurate.
Loose diamonds also matter for determining color. Depending on the precious metal the diamond is set in, the jewel may appear lighter or yellower than it actually is. Some diamonds are specifically set to give the illusion of a different color. The mounting may also influence how much light travels through the jewel, creating an inexact color grade.
Part of the GIA certification process involves testing to determine the presence and types of clarity characteristics. With loose diamonds, clarity characteristics are easier to find, as the jewel can be viewed from more angles that one that is mounted. The presence of treatments is also easier to find with loose diamonds for similar reasons.
For the clearest results, send loose diamonds to GIA for grading. GIA will not unmount or remount diamonds, so you should send in your jewels before you have them set into rings or other pieces. You may also ask your jeweler to remove your diamonds from their mountings for you.
How to Tell Diamonds Apart
Whether rough or cut to exacting standards, diamonds are a pleasure to look at. However, it’s not always easy to distinguish one stone from another. If someone experiences a mix up with their loose diamonds, how can they be sure which jewel is which? Part of the diamond certification process involves searching for a jewel’s fingerprint.
One of the qualities diamonds are graded for is clarity, or the quirks on inside the jewel. Clarity characteristics may range from an extra facet on the girdle to other minerals mixed within the crystal. No two diamonds have their clarity expressed the same way, giving jewelers and connoisseurs a means to identify certified diamonds.
GIA certified diamonds which have Diamond Reports come with a diagram plotting the locations of clarity characteristics as they appear from the top and bottom of the jewel. A legend at the bottom of the report denotes which symbols represent what clarity characteristic. Diamond Dossiers have an abbreviated certificate. While their papers note which characteristics are inside the jewel, they come without illustrations.
Another marker of a diamond’s identity is the presence of fluorescence. Twenty five to thirty five percent of diamonds glow when exposed to ultraviolet light. Most diamonds with this trait emit blue light, though orange and yellow light may also occur. The fluorescence of GIA certified diamonds is graded by None, Faint, Medium, Strong and Very Strong.
During grading, loose diamonds’ proportions are measured. Total height is accounted for, along with pavilion depth, crown height, girdle thickness, table diameter and so on. The dimensions help to determine the quality of the brilliance as well as serving clues to a diamond’s identity. Size is also measured, by both carat weight and millimeter.
One last, optional step is for GIA to inscribe certified diamonds with unique ID numbers onto their girdles. The number itself is very small, with minimal impact on the gemstone’s appearance. GIA uses lasers to inscribe the ID, using precision and tremendous amounts of heat to remove some of the diamond’s carbon, leaving an etching behind.
GIA and the 4Cs
Beauty is in the eye of the beholder. What appears to be a plain diamond to some may be understated elegance to another. When buying a diamond, many want to be sure of its quality, and that it was evaluated by a trustworthy source. The Gemological Institute of America developed the concept of the four Cs of carat, clarity, color and cut to create an objective standard for certified diamonds.
Carat refers to the size of a gemstone. It’s a unit of weight measurement that’s one fifth of a gram, or 20 milligrams. To best determine the weight of loose diamonds, the stones are placed on scales so sensitive, they have chambers to discourage breezes from skewing the results. GIA uses scales which measure to the hundred thousandth of a carat, or five numerals from the decimal point. It’s then rounded to the nearest hundredth of a carat for the report.
For most diamonds, lighter colors are considered ideal. The large majority of diamonds mined have traces of yellow or brown. GIA’s color scale measures the degree of tint in loose diamonds, with D having no color at all and Z with a tinge apparent to the naked eye. While there are diamonds with colors stronger than Z, they are subject to a different grading system.
Due to the conditions natural diamonds form under, flawless diamonds are very rare. Many stones feature pinpoint imperfections, other minerals within their stone, internal fractures and other quirks. GIA certified diamonds are examined for clarity under 10x magnification, and their clarity characteristics are catalogued and plotted on a diagram. Grades range from Flawless to Included 3, with most gemstones falling in between.
Determining the quality of a diamond’s cut is complex. What style of cuts make beautiful loose diamonds can be subjective. GIA concentrates on grading the round brilliant, with its strict standards for quality, with grades ranging from Excellent to Poor. The stone’s proportions and angles are studied, its facets counted and measured. A skilled cut should have a balance of brilliance, fire and scintillation.
Diamonds and Diamond Simulants
Loose diamonds are attractive yet costly. It’s not uncommon for people to wear jewelry with inexpensive gems that resemble diamonds. Some may even wear diamond simulants for casual occasions, switching to real gemstones for special occasions. Though simulants serve a purpose, it’s problematic if a person isn’t sure if their jewels are authentic. Fortunately, there are ways to determine the nature of a stone.
There is folklore that offers simple tricks to determine a diamond’s authenticity. One legend says that only a diamond can cut glass. In truth, sapphire, topaz, quartz and other substances with a Mohs hardness of 6 or higher is able to scratch glass. Another story states that loose diamonds can be verified by whether or not the stone sparkles. While diamonds are famed for their brilliance, their ability to reflect light depends on its cut, ambient lighting and the cleanliness of the stone.
A reliable way to distinguish a diamond from a simulant is through certification from an independent third party laboratory. Organizations like the Gemological Institute of America use trained gemologists and advanced equipment to help determine the authenticity of gemstones. GIA certified diamonds also come with diagrams detailing a diamond’s unique clarity characteristics, the proportions of the jewel, and other traits which verify the stone. Those who want extra peace of mind in distinguishing their stone may have GIA inscribe an ID number onto the diamond’s girdle.
Which of the 4Cs Matters to You?
The four Cs of carat, cut, clarity and color were developed by the Gemological Institute of America in the 1950s as a standard for diamond grading. Even today, GIA certified diamonds come with a report detailing their 4Cs. While each factor comes together to contribute to a diamond’s beauty, it’s up to the individual what aesthetics they want in a jewel. When it comes to choosing loose diamonds, you may want to think about the 4Cs and how they relate to your tastes.
Carat is a unit of measurement used to determine the size of the diamond. Due to the extreme conditions diamonds form in, larger jewels are rarer than smaller ones. A person may prefer the aesthetics and value of four quarter carat diamonds, while others may prefer making a statement with a single jewel one carat or larger. Certified diamonds aim to provide a precise measure of a diamond’s carat. GIA certified diamonds are measured on powerful scales designed to reduce as many variables as possible when weighing stones.
A diamond’s cut is more than its shape. How a gem is faceted and polished determines its luster, brilliance, scintillation and other optical properties that highlight the jewel’s beauty. Certified diamonds are examined for symmetry, total depth, facet angles and other factors to determine how well the stone takes in and reflects light. Connoisseurs who enjoy brilliance and luster may want jewels with a high cut grade.
Diamonds often bear side effects of the environment from which they formed. Clarity grades gauge the type and amount of inclusions, or clarity characteristics, of a diamond. GIA certified diamonds are examined under 10x magnification and graded on a scale of eleven ratings from Flawless to Included 3. Those who desire diamond cuts which showcase the interior of the jewel may wish to seek diamonds with higher clarity grades such as Very Slightly Included 1.
GIA certified diamonds are color graded from a scale of D to Z, from colorless to light. The closer a diamond is to Z, the more apparent its yellow or brown tint. Nitrogen, which gives these colors to diamonds, appears as a trace element in over 95% of the jewels. Diamonds with a D or E grade are quite rare and may be sought out for their uniqueness. Those who wish for a stone to coordinate with a platinum or white gold setting may prefer jewels rated H or higher. Others who like a visible touch of color to their diamonds may want to look at gemstones from S to Z.