Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice.
Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at standard conditions.
Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice..
it can be contaminated by very few types of impurities, such as boron and nitrogen. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion (ability to disperse light of different colors).
With fewer imperfections within the stone, the diamond is more rare and has a higher value. The clarity scale was developed by the Gemological Institute of America (GIA) to quantify these imperfections. The American Gem Society (AGS) uses the same standards as the GIA; however, the AGS uses a numerical system where "0" is the cleanest (GIA "IF") and "10" is the most imperfect (GIA "I3").
All diamonds are systematically graded and plotted under 10X magnification. If a trained grader cannot see a clarity characteristic at 10X, it does not affect the clarity grade.
Diamonds come in a variety of colors, some of them highly prized (pinks, blues, even yellow). However in a white diamond, the presence of a yellow tint will lower the price of a diamond. The less body color in a white diamond, the more true color it will reflect, and thus the greater its value.
Every Lumera Diamond has been assigned a color grade by the GIA in a viewing environment specially designed to eliminate color from surrounding surfaces as well as the light source itself.
This allows the color of the diamond to be accurately measured. Minor differences in diamond color detected in this environment are very difficult if not impossible to detect in a normal environment. The diamond industry has adopted the GIA diamond color scale; almost every diamond sold today is rated using the GIA color scale, whether it was actually certified by the GIA or not.
Cut refers not to a diamond's shape (e.g. round, oval, pear, etc.) but to a diamond's proportions, symmetry and polish.
The beauty of a diamond depends more on cut than any other factor. Though extremely difficult to analyze and quantify, diamond cut has three primary effects on appearance: brilliance (the brightness created by the combination of all the white light reflections from the surface and the inside of a polished diamond), fire (the dispersion of light into the colors of the visible spectrum, seen as flashes of color), and scintillation (the flashes of light and dark, or sparkle, when a diamond or light source is moved).
When a diamond is fashioned from a rough stone, the cutter must balance optimal cut (and therefore appearance) against maximum yield (cutting the diamond to maintain as much carat weight from the rough stone as possible). Because many customers are willing to pay more for a larger, fair-cut cut diamond than for a slightly smaller, well-cut diamond, there is pressure on the cutter to sacrifice appearance for weight. This is why the Cut grade is so important; it allows the purchaser to identify those stones that were cut Fair to Poor in an effort to gain carat weight.
Symmetry refers to how precisely the various facets of a diamond align and intersect. This can include extra or misshapen facets, off center culets and tables, and wavy girdles.
A diamond with poor symmetry may misdirect light that travels into the diamond, sending it off at slightly wrong angles, and thereby reducing the diamond's brilliance. Often, a diamond cutter will purposefully allow a minor reduction in symmetry as a way of preventing a defect present in the rough stone from being retained as part of the finished diamond.
For diamonds with a symmetry grade of Excellent to Good, symmetry should not be used as a primary factor in choosing a diamond, since each of these grades is possible in diamonds of exceptional appearance.
Symmetry is more important in diamonds of VVS2 Clarity and higher, since the very subtle defects produced by Fair or Poor symmetry (which can resemble pinpoint inclusions) would compromise the diamond's otherwise flawless appearance.