When grading a gemstone there are 4 specific factors that come into play, hence the 4 c's. The 4 c's represent color, cut, clarity, and carat weight. Some of these variables are visible to the naked eye, some are not.
Learn more below.
Color
Gemstones of all origins come in different shapes, sizes and colors. For instance a ruby's red can range from a pinkish tint all the to a dark red similar to garnet. Gemstones color are graded based on 3 factors: hue, saturation and tone.
Hue can describe the actually color of the gemstone. A ruby's red or an emerald's green. However the hue of a gemstone can also be in-between colors, i.e. pink/red ruby.
Saturation describes the intensity of the hue(color). The gemstones that are graded the highest are those with high saturation ~or~ the brightest color.
Tone is used to describe the tint of the color. The ideal tone for a gemstone lie about right in the middle of the spectrum. When a gemstones tone is either too light or too dark the value drops.
Cut
The cut of a gemstone refers the shape of the gem itself. Gemstones come in a variety of popular shapes including emerald cut, pear cut, princess cut, etc. Each unique cut providing it's own distinctive style.
Many variables come into play when grading the cut of a gemstone with the most important being the critical angles which will ultimately decide the brilliance of the gemstone. The brilliance refers to how much light gets trapped inside of the stone, giving it that sparkle that everyone loves to look at.
Clarity
The clarity of a gemstones refer to the internal landscape of the gemstone. Throughout the natural process that gemstones undergo during their creation can often leave them with inclusions. Inclusions are blemishes that the gemstone has and are detrimental to a gemstones grading.
*Blemishes can be chips, scratches, abrasions, etc.*
Carat Weight
This simply means how much the gemstone weighs. The bigger the gemstone more valuable it becomes. Carats are about 1/5 of a gram and are vital when grading gemstones. The carat weight of a gemstone should be specified to the 1/100. For example, gemstones should be weighed as 8.65 or 4.34 carats.
Some jewelry websites don't list the carat weight and this can be dangerous for the buyer. When purchasing gemstones, or anything for matter, it's important to be educated otherwise it can be easy to get mislead.