Cut is the only human contribution to the diamond's beauty; however, it is one of the most important factors. The term "cut" can mean many things. In the jewelry industry is used to describe the shape, cut style, proportions and finish of a diamond. Diamonds can be cut into almost any shape. The most popular shapes are round, cushion and radiant..
GIA's diamond cut grade predicts levels of brightness, fire, and scintillation, which indicate how well a diamond's proportions work together to return white and colored light to the observer. Face-up appearance, design and craftsmanship are critical to a diamond's overall cut quality. Weight ratio, durability, polish and symmetry are all included in GIA's Diamond Cut Grading System.
How a diamond handles light
- When a diamond is cut to good proportions, light enters the stone and is reflected from one facet to another and then dispersed out through the top of the stone.
- If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion.
- If the cut is too shallow, light escapes through the pavilion before it can be reflected, thus reducing brilliancy.
The color scale to the right reflects how closely a diamond approaches the colorlessness.
True colorless diamonds are quite rare and only make up a small fraction of all mined diamonds (Colors D-F); therefore most jewelry is made using diamonds in the near-colorless range (Colors G-J).
Diamonds are also available in a variety of colors including red, purple, pink, green, orange, yellow, blue, brown and black. These extremely rare and unique diamonds are termed "Fancy Colors". Their color is more saturated than a Z color diamond and they are graded based on the hue, tone and saturation of their color. The more intense the color, the higher the rarity factor. The rarest of the fancy colors is red.
The clarity grade is the degree to which the diamond is free of inclusions and blemishes. Nature produces very few things that are absolutely perfect. Most diamonds have internal birthmarks, known as inclusions, and external characteristics called blemishes. These clarity characteristics are evaluated under 10X magnification, by trained diamond graders, based on the number, nature, size, location and color of each characteristic. Clarity characteristics are also used to distinguish one diamond from another. A diamond's inclusions are like a fingerprint, making each diamond one-of-a-kind. Flawless diamonds are extremely rare and command the highest prices, but finding a diamond with minute or minor inclusions can reduce the cost of the stone without detracting from its beauty or durability.
Also available are a small percentage of natural diamonds that have been clarity enhanced by chemical infusions and laser treatments. Clarity enhanced diamonds are typically offered at significant savings therefore they are a great way to get a bigger look for your money.
Fracture Filling (Clarity enhanced by Chemical Infusions)
Fracture filling is a process for filing structural separations (feathers) that occur naturally during the growth of a diamond, or during the cutting process. Its purpose is to reduce the visibility of feathers which stand out in high relief compared to the rest of the diamond. The feather is filled with non-permanent filler that has a refractive index close to diamond, making it less noticeable. A jeweler can identify a fracture filled diamond by looking for a flash of color, or the "flash effect". Fracture filled diamonds may appear to be one to two clarity grades higher after enhancement, while color grade may decrease in some diamonds. It is important to notify your jeweler that your diamond has been fractured filled before they begin any repair work on your piece to ensure they use the appropriate care.
Laser drilling is done to remove or minimize the visibility of a dark inclusion in the diamond. A laser is used to create a microscopic tunnel from the diamond surface to the inclusion, therefore allowing light to reach the inclusion. If further treatment is needed, an acid is injected through the drill hole to "bleach" the inclusion. The clarity grade of these diamonds is seldom changed after drilling, the original inclusions are still there and the laser hole itself is another inclusion. The positive benefit is that it does improve the appearance of the diamond. Laser drilling is not considered detrimental to the durability of the stone; therefore no special requirements are necessary in caring for these diamonds.
Diamonds are weighed on a scale of metric carats, abbreviated "ct." It is equal to approximately 1/5 of a gram. A carat is broken down into 100 points, just like a dollar is broken down into 100 pennies. When you see a diamond weight of 1.45 ct., it means one carat and 45 points.
The larger a diamond is, the more rare it is. Diamonds are bought and sold on a pricing concept know as "per carat." As diamonds get larger, the price per carat increases due to the rarity factor - a diamond that weighs 2 ct. will be worth more than twice as much as a 1 ct. diamond.