History of the Carat

The "carat" is the weighing standard used in the gem industry since antiquity. This system of measurement traces its roots from many centuries ago when early merchants & dealers of diamonds used carob seeds as their scale counterweight. They much preferred the carob seeds because of their uniform weight making it easier for them to trade using a common measurement.

It was not until the early 1900's that Europe & America, along with most countries, adopted the Metric Carat of 200 milligrams or 0.2 gram which up until now is still the current standard. Each metric carat is subdivided into fractions (ex. 1/10ct) or decimals (ex. 1.25ct) up to 2 decimal places. It can also be divided into 100 parts or "points" similar to a dollar having 100 pennies (ex. 0.50ct = 50 points).

Prices of diamonds are for the most part based on its carat weight. The price of diamonds go up progressively in relation to its weight but not in a directly proportional way . You may think that a 2.0 carat diamond would cost twice as much as a 1.0 carat diamond but the truth is that it would be more than twice the price. Why is that? Because a larger diamond occurs lesser in nature than smaller ones.

Please refer to the chart above for a weight-to-diameter relation. The diamond sizes shown in the image are not the actual diamond sizes - please use the sample images only to compare relative proportions.

Diamond Clarity

Through natural geological processes that occur inside the Earth's upper mantle, carbon atoms bond and crystallize to form the precious rocks we call Diamonds. During this very long process, occurrences such as irregular crystallization and mineral compacting may happen. The former leads to the formation of "feathers" and the latter to black internal spots - both what gemologists and jewelers call impurities or "inclusions".

Impurities or inclusions affect the a diamond's desirability because it affects its cosmetic appearance and in part because they interfere with the flow of light into and out of the crown of larger diamonds. Less inclusion means a much better looking clear diamond which translates to more value.

Because of the importance of knowing a diamond's clarity, the first grading system for it was introduced in the 1950's called the "Diamond Grading and Evaluation Appraisal". This evaluation scale initially had 9 grades: Flawless (FL), Very, Very Slightly Included 1 & 2 (VVS1 & VVS2), Very Slightly Included 1 & 2 (VS1 & VS2), Slightly Included 1 & 2 (SI1 & SI2), Included 1 & 2 (I1 & I2). During the 1970's, diamond production trends led the Gemological Institute of America (GIA) to expand this system by introducing 2 new values: Internally Flawless (IF) & the I3 grade. To date, GIA's evaluation is still the widely accepted method of clarity grading.

By using magnification & illumination procedures done in a laboratory, a gemologist can assess a diamond's clarity. With a GIA certified diamond, the certification is done using a 10x with darkfield illumination. Using established techniques, GIA gemologists record & identify in complete detail all the positions, sizes, colors, nature, & number of the inclusions in the diamond.

Clarity Enhanced Diamonds

With a steady source of diamonds, the prices of these much coveted diamonds became more affordable for the vast market. Backed by a culture who has embraced has diamond as the symbol of "forever," demand for it only increased the need for leading jewelers to find new ways of delivering better products.

It is a known fact that some diamonds were just made by nature to be of lesser quality because of their natural inclusions. Though low-clarity diamonds are considerably less expensive compared to their more "clean" high-clarity counterparts, people who know enough would still prefer the latter. To bridge the lack of "cleanness" of the said stones, enhancement methods like Laser Drilling & Fracture Filling were then developed in hopes that improving their quality would lead to a much better demand.

Laser Drilling

Through the use of a precise infrared laser, microscopic holes are drilled on the diamond to create tubes that will have access to the inclusion. Once area of the inclusion is breached, the diamond can either be immersed in sulfuric acid or treated in acid to melt away crystal inclusions or iron oxide stains.

Fracture Filling

An enhancement pioneered bu Zvi Yehuda of Ramat Gan, Israel, fracture filling uses a specially formulated oxychloride glass compound which has near to almost the same light-refractive index of the diamond that it will be used for. The glass compound used has a low melting point and is usually introduced to the inclusion via micro-tubes created by Laser-Drilling.

The process is not immediately visible to the naked eye and can only be easily seen by a trained jeweler or gemologist under close magnification. Minor color-changes have also been noted before but are only clearly visible under very close scrutiny but the overall product is a diamond that, to the naked eye, is of a much higher clarity grading.

Diamond Color

If formed perfectly at the atomic level, diamonds should be able to allow light to pass through without any of the color from the light spectrum to be absorbed. This perfect formation would render a diamond as a perfect "white" diamond. However, because of random occurring conditions & substances in nature, it is not at all possible for diamonds to naturally form in this ideal manner.

During natural crystallization, diamonds get subjected to extremely high temperatures rendering its atomic structure open to bonding with atoms from other elements such as nitrogen & boron. Diamonds that have bonded with nitrogen in them range in color from pale to deep yellow, orange, brown, or greenish. Those that have bonded with boron (very rare), on the other hand, range from blue, grey, to nearly colorless.

Because each diamond color fetches a different price, competing parties in the diamond trade started the use of color grading to group similar colored diamonds. The many early & competing grading systems led to a lack in consistency in the trade and caused problems for diamond traders. This lack of a common evaluating method was finally fixed by the Gemological Institute of Diamonds (GIA) when they introduced their diamond color grading system.

Wanting to start a system that is free of any association from earlier systems of color grading, GIA use the letter "D" as their topmost value for a diamond's whiteness. From "D" all the way to "Z", the scale turns gradually from the ideal "white" diamond color to fancier shades of yellow. Diamonds that have colors beyond the "Z" color grade are subject to a different system that also details the characteristics of its color.

Because color evaluation can be subject to the observer, GIA uses "masterstones". Each color-grade has an assigned masterstone and the diamond to be evaluated are then compared to them. Another means of grading a diamond's color is through the use of a Gran Colorimeter. First developed by Paul Gran, the Gran Colorimeter can measure diamond grades from D all the way past Z to "Fancy Intense" to an accurate degree. Furthermore, it can also use other color-grading systems like GEM, IGI, AGS, HRD, and more.

Color Enhancement & Treatment

Perfect white diamonds fetch very high prices because they are rare. Even much more rare are colored diamonds in the following colors: intense red, intense green, intense purple, blue, & pink. Because of their high prices & extreme rarity, however, many avid jewelry lovers would just have to opt for artificially treated diamonds.

Irradiation

While conducting his experiments, Sir William Crookes, a chemist, physicist, & gem expert discovered that radium salts enveloped around a diamond gradually turned green. From this early discovery, newer & safer irradiation methods have been developed to treat diamonds and change their color. The main idea of the newer irradiation methods is to create color centers in the diamond by knocking out or forcing carbon atoms around. Colors known to have been produced by irradiation range from green, black, or blue. These irradiated diamonds can then be heated to further modify their atomic arrangement to create bright shades of brown, orange, pink, and yellow.

Surface Coating

Special dyes can be used to color-treat diamonds to make them more translucent-looking or brighter to the naked eye. Though most of coating treatments can be undone by constant exposure to hot water or alcohol, some may require significant expertise to remove or even detect the presence of the treatment. Notable in this category of treatment is that jewelers are legally bound to disclose all information on any previous treatment of a diamond prior to a sale.

High Temperature, High-Pressure (HTHP)

First introduced in 1999 by General Electric (GE), HTHP was used to improve the color saturation of diamonds. Each diamond treated using GE's process is subjected to extreme temperatures as high as 3,632°F (2000°C) and pressures of up to 70,000 atmospheres.

The same year that GE introduced their diamond treatment technology, a company specializing in diamond synthesis named Novatek accidentally discovered that HTHP can result to a diamond's color to change. This newfound result was further developed to turn brown diamonds to light yellow, yellowish-green, or greenish-yellow; improve light yellow diamonds to make them closer to white; increase color-saturation for yellow diamonds, and render some bluish diamonds colorless. Diamond treated using these two techniques should also be disclosed prior to a sale.

Diamond Cutting & Shapes

A diamond's brilliance is what makes this stone the most coveted of all gems. Early people believed that these stones were fragments of stars and even tears from the Gods themselves. Even the early Kings, Queens, and people of power have taken to diamonds as a symbol of their strength & courage because of their naturally reflected "fire".

With the desire to enhance this brilliance, early jewelers and artisans started cutting and faceting their diamonds. Prior to the 1900's, the process of refining a diamond rough to a finished cut diamond such as a Rose Cut, Old European Cut, or Old Mine Cut had been mostly done by hand. With the coming of technological advances and discoveries in optics, modern cutting & polishing styles were introduced with the goal of maximizing the play of light inside a diamond. The antiquated cutting styles were then gradually replaced the more modern diamonds we know such as the round brilliant & princess cuts.