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Diamonds represent a world of glitz, sparkle and color They are projected in various sizes, shapes, and characteristics – which summarize their intrinsic value. However, this makes the choice of a good piece of diamond quite tricky.
Expert jewelers and graders possess the adequate experience to judge the quality of diamond using a systematic grading system and can help you with choices when necessary. However, having prior knowledge - however minimal - before a purchase is advantageous.
Luckily, consumers can also glean from the universal grading elements known as the 5Cs to ascertain the features of the diamonds in hand. In this guide, we highlight the unique system of grading the quality of your diamond.
The 5Cs of Diamond Grading
Until the middle of the twentieth century, there was no official standard by which diamonds could be graded. Gemological Institute of America (GIA) created the first, and now globally accepted standard for grading diamonds: Color, Clarity, Cut and Carat Weight. Today, the universal standards for assessing diamond quality have adopted certificates as the 5th C.
The diamond carat is perhaps the most important feature of the 5Cs. It is the unit or value of the weight of diamonds.
The weight of goods is invariably a measure of the cost of those goods. Larger goods are typically valued more than smaller ones, so carat weights represent a world of value to diamonds.
A digital scale measures diamond carat weights, and measurements are stated in metric carats (ct). One gram represents five metric carats in measurement, while about 142 metric carats represent one ounce.
Metric carat measurements are divided into 100 points with one point a hundredth of a carat. For example, a diamond that weighs 0.86 carats will be said to weigh eighty-six points. Diamond carat weights are also presented in decimals and carats. A diamond weighed at 1.04 carat will be addressed as “one point oh four carat.”
The approximation of these units of measurements determines price variations. This is why you’d find a larger diamond more expensive than two smaller diamonds of the same quality. However, it is noteworthy that the price correlations based on the carat weight of a diamond are variable and subject to other aspects such as the diamond cut, diamond color, and diamond clarity.
Slight variations in diamond color can influence the value. Two diamonds can be of the same diamond carat weight and have other similar features but a color change can dramatically impact the price. This is why color is a crucial factor in ascertaining the quality of your diamond.
According to the Gemological Institute of America (GIA), diamond color ranges are based on a 23 grading scale that ranges from D to Z with sections classified as:
Colorless (D to F)
Near colorless (G to J)
Faint (K to M)
Very light (N to R)
Light (S to Z)
Several conditions should be noted when choosing a diamond color. These conditions include the setting, the lighting conditions of the room, and the background used for checking. A simple way of telling the diamond color is by laying it face down on a white sheet of paper in a well-lit environment.
A well-cut diamond is an aesthetic display of creative craftsmanship and so, diamond cuts are a vital quality determinant. A beautifully crafted diamond is a reflection of its polish and proportions. The proportions determine the direction the light travels through the diamond while its polish determines how it appears to the eye.
When held against the light, the way you see a diamond is due to three optical effects: the Brightness i.e., white light reflections, Fire i.e., color flashes, Scintillation i.e., light and dark areas.
Like color, diamond cuts are subject to grading systems that range from 0 to 10. An ideal diamond cut will be graded 0 while a poor diamond cut will make the 8 to 10 mark. It is, however, noteworthy that diamond cut and shape differ.
Fancy shaped diamonds come with names of their own. This is why you’d come across pear, oval, princess, heart or emerald-cut diamonds. However, the fancy cut is not a determinant of the quality of the cut. You can have a poorly cut emerald-shaped diamond.
The diamond clarity rating ultimately determines the excellence of your diamond. Though they are considered as nature’s gift, natural diamonds are subject to surface imperfections and inclusions. These imperfections invariably affect diamond clarity and value.
The diamond clarity characteristics are graded via 10x magnification examinations, after which they are placed on an 11-grade scale. When referring to inclusions, gemologists often use the term “internal characteristics” instead of flaws.
Diamonds with poor clarity grades are prone to accidental damages such as cracking, shattering, or chipping. In some cases, low diamond clarity makes the gem give off less brilliance in appearance despite the light conditions.
Diamonds with the fewest and smallest inclusions receive the highest diamond clarity grades.
A diamond certificate is a document prepared by a trained gemologist in a diamond grading laboratory, after a thorough assessment of all the defining features on your gem. The certificate itself does not affect the final price of your stone, however, it lists all the qualities, additional processes and enhancements that may affect the value of your diamond. The certificate also states whether your diamond is natural, lab-grown or enhanced.
It is important to double check the consistency and reliability of the grading laboratory that issued a diamond certificate before making your final purchasing decision. Some grading laboratories follow different standards and therefore may reward significantly higher or lower grades compared to the existing international standard. The most internationally recognized diamond grading laboratories include; Gemological Institute of America (GIA), American Gem Society (AGS) and International Gemological Institute (IGI)
Beyond the quality determinants of your diamond, it is also important to understand the properties of diamonds in order to ascertain the legitimacy of the diamond in hand.
Natural diamonds are classified as excellent electrical insulators.
Though good conductors of heat, they can withstand high levels of heat without changing form. Diamond will oxidize in the presence of oxygen when heated up to 7000C and remain stable in the presence of ideal gases such as Argon. Diamonds can withstand over 30000C under certain pressure levels.
Diamonds (both natural diamonds and lab-grown diamonds) exhibit fluorescence. They emit and reflect light of different colors under appropriate wavelengths (365nm).
The basic physical properties of diamonds include:
Color ranges from colorless, pale yellow, blue-white to rare reds, grey, and blacks.
The density of natural diamonds ranges from 3.5 to 3.53g/cm3. This value may differ in the case of lab-grown diamonds.
Natural diamonds are brittle and have a Mohs hardness grade of 10 – typically the hardest naturally occurring material.
They can be transparent, translucent, sub-transparent, or opaque.
The typical natural diamond luster will range from adamantine to greasy based on the cut though they have a colorless or white streak.
The crystal system of diamonds is isometric and the fracture pattern is majorly irregular.
Though the hardest naturally occurring material, the perfect cleavage of natural diamonds (as well as lab-grown diamonds) makes them susceptible to shatters when placed under the right amount of pressure.
Chemical Properties
The chemical properties of diamonds include:
They crystallize in the diamond cubic crystal system (space group Fd3m) and consist of tetrahedral, covalently bonded carbon atoms.
High resistance to acids but will dissolve in hot steel.
They have no boiling point.
Contrary to popular belief, lab-grown diamonds are real diamonds. The only significant difference between lab-grown diamonds and natural diamonds is their origin. They possess the same sparkle, lattice arrangements, and properties as natural diamonds.
As such, the differences are quite impossible to spot, especially when it comes to visual recognition. However, gemologists and industry leaders use specialized laboratory equipment to differentiate between the two.
Lab-grown diamonds cost less than natural diamonds by about 20 to 40 percent on average. This is due to the mining costs and sustainability of the purification process. Consumers that are particular about environmental sustainability usually forego mined or natural diamonds for their lab-grown counterparts.
Diamond grading reports and certificates also confirm if a diamond is natural or lab-grown. Overall, the best diamond grading laboratories for both natural diamonds and lab-grown diamonds are the GIA, AGS and IGI, because they give specific and detailed grades on each diamond feature.
Whether you’re looking for a perfect gemstone for an engagement ring or classy stones for a beautiful piece of jewelry, nothing makes a statement like the sparkle of a diamond. However, before splurging on one, take time to study its quality first.
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