Crystal Quality

Diamond is the only stone that has strict universal grading standards.  All other precious and semi-precious stones are graded more casually, taking their cues from diamonds.  Fine gemstones like Sapphire, Emerald, and Ruby are typically graded by professional gemologists.  Some gemologists also deal with the many other stones sold as healing crystals. The majority of industry experts who grade stones due so according to their own personal experience and preference.

The grading system for diamonds was developed in the 1950s by the GIA (Gemological Institute of America).  Quality is judged by the 4Cs – Color, Clarity, Cut, and Carat weight.  Each factor is rated independently and the final value of the diamond is determined by the combination.  The rarer the combination, the higher the price.  The most precious diamonds are either usually completely colorless, although a rare vivid color such as blue, such as the Hope Diamond, is also very valuable.  The most expensive diamonds are also flawlessly clear, beautifully cut, and large.

Diamonds are graded on a color scale of D-Z.  Interestingly there is no such thing as an “A Grade” Diamond!  While most people think of diamonds as a colorless gem used in expensive jewelry, only a small percentage of diamonds meet the strict quality standards for fine gemstones.  Diamonds that are N-Z grade are typically used industrially, for example in diamond-tipped tools.  These diamonds don’t look very remarkable, but they have an exceptional hardness that makes them very useful.

Of the 4cs, Color and Clarity are the most strictly regulated, while Carat weight is the simplest to calculate.  These three factors are all gifts from Mother Nature. By contrast, Cut is due entirely to the work of skilled artisans.  A high-quality cut creates the facets which reflect light in a dazzling display.  Round diamonds are the standard shape, everything else is known as a “fancy cut.”  The brighter the dazzle, the more expensive the diamond.

Colored Stones used in fine jewelry are also judged by the 4Cs.  Cut and Carat weight are the same as in Diamonds, but Color and Clarity are much more subjective!  For one thing, color interpretation is unique to each person, and lighting can also dramatically change how a color appears.  To further complicate the matter, many stones have multiple colors, such as blue-green, or reddish-purple.  In a small company, a single person might be tasked with judging each stone’s color and deciding how to characterize it.  In larger companies, two or more people may have to independently judge each stone.  While care is taken for accuracy, it is still a subjective judgement.  Color is based on hue, tone, and saturation.  The hue is the basic color, for example “blue,” while tone is how light or dark it is.  Saturation is the most important factor; this is how intense the color appears.  The best quality colored stones are called “Vivid,” the next best saturation is “Intense.”  For Clarity in diamonds, the goal is typically to be “flawless” with no inclusions whatsoever.  For colored stones, the goal is to be “eye clean” since inclusions are what give these stones their color.

An example of a particularly exquisite colored stone is “The Titan’s Eye” owned by the Natural Sapphire Company and available for just under 3 million dollars.  This ultra-rare natural Blue Sapphire is one of the largest in the world at 69 carat weight.  Its color is “intense,” its clarity is “eye-clean,” and its cut is an oval.