Clarity is a description of the purity of the diamond. Sometimes called ‘natures fingerprints’ (because they make each gem unique), inclusions are flaws within the diamond. Blemishes are external flaws caused by the diamonds crystal structure, the cutting process, or wear. For the purposes of diamond clarity grading, all flaws are considered “inclusions.” Flawless or nearly flawless diamonds are the most rare and therefore the most valuable.

Diamonds are brilliant because of the way light passes through them and is reflected back. Inclusions can affect the path of the light decreasing its ability to transmit the light through and out of the stone. Diamonds with fewer inclusions have more fire and brilliance and are more valuable. A diamond is one of the hardest substances found in nature, but some inclusions can make a diamond more prone to breaking or shattering. Partially because of their low clarity, about 80% of all diamonds are not suitable for use as a gemstone and are restricted to industrial use.

Typical internal flaws or inclusions

Carbon spots — black spots that look like pepper
Crystal — another mineral or crystal within the diamond structure, which can include other diamonds. Some think of them fondly as “baby” diamonds.
Pinpoint — a tiny crystal that looks like a speck of dust, often found in groups.
Needle — thin, long crystal
Cloud — cluster of small white crystals that look cloudy or milky
Knot — an included diamond crystal that continues to the surface after polishing
Feather — a separation due to fracture or cleavage which has a feathery appearance
Cleavage — a straight crack which is not feathered
Cavity — an opening or space at the surface of the diamond
Bearded girdle — hair-like stress lines that extend to the girdle
Internal graining — faint lines, curves or angles caused by irregular crystal growth
Laser lines — appear when lasers have been used to artificially improve a diamonds clarity grade

Common external flaws or blemishes

Nick — a small chip
Scratch — thin white curved or straight line across the diamonds surface
Abrasion — series of small nicks
Fracture — a crack on the stones’ surface
Pit — a small surface opening that looks like a white dot

Diamond clarity is graded by the GIA using a letter and number scale, and by the AGS using a number scale where 0 indicates the best clarity and 10 represents the worst. While the GIA scale can appear confusing, the letters are abbreviations for real words that tell you about the clarity.

FL=Flawless — no internal or external flaws. The most rare diamond clarity, and the most valuable. Unsurpassed fire and brilliance.
IF=Internally Flawless — no internal flaws, but there may be minor surface blemishes.
VVS1-2 = Very Very Slight inclusion (VVS1 is a slightly higher clarity than VVS2). It is difficult for even a trained gemologist using the standard 10x magnification to find the imperfections in a VVS1-2
VS1-2 = Very Slight inclusion — Still only visible with 10x magnification and a practiced eye.
SI1-2 = Slight Inclusion — Noticeable inclusions when using 10x magnification and sometimes visible to the naked eye.
I1- Imperfect or Included — inclusions which are visible to the naked eye with no magnification
I2-3 = Imperfect or Included — Visibly obvious inclusions which can effect the path of light and therefore decrease a diamonds brilliance.

Carat weight is a measure of the weight of a diamond, but many people think of it as its size. A carat is a unit of weight equal to 0.2 grams. Within the industry, the carat weight is commonly referred to as its “points.” A 1 carat diamond would be 100 points. A diamond weighing 0.5 carats would be a 50 point or ½ carat diamond.

A colorless, flawless is diamond is rare, and large colorless flawless diamonds are even more rare. When comparing two diamonds of equal color, clarity and cut, the higher carat weight diamond will be more valuable. Alternatively, a 2 carat diamond with low clarity and carat weight may be less expensive than a 1 carat or smaller diamond of much higher quality.