Certification (or Diamond Grading Reports) — There are many recognized gemological laboratories that can grade your stones for a fee. The most well known are GIA and EGL. .
Carat — Unit of measure of weight of diamonds and gemstones. One carat is equivalent to 200 milligrams. One carat can also be divided into 100 “points.” A .75-carat stone is the same as a 75-point or 3/4-carat stone.
Clarity — A diamond often has natural imperfections, commonly referred to as inclusions, which contribute to its identifying characteristics. Inclusions are found within the diamond, and can be white, black, colorless, or even red or green. Most are undetectable by the human eye, and can only be seen with 10X magnification. Inclusions are ranked on a scale of perfection called clarity.
Color — Diamonds are graded on a color scale established by the Gemological Institute of America (GIA). Fancy colors refer to diamonds with hues like pink, blue, green, yellow, and very rarely red. Fancy colors are not included in this color scale and are considered extremely rare.
Brilliance — Liveliness, or sparkle in a stone when light is reflected from the surface and from the total internal reflection of light.
Scintillation — When light reflects from a diamond, the sparkling flashes that come from the facets of the gem are known as scintillation.
triangular, square, marquise, pear, oval or heart-shaped.
Symmetry — Symmetry is the arrangement of the facets and finished angles created by the diamond cutter.
Inclusion — “Internal characteristics” apparent to a trained or professional eye at 10x
Proportion — The proportions of a diamond are very important, so that the maximum amount of light be reflected off and out of a stone. Proportion is the relationship between the angles of the facets of the crown and pavilion.
Shape — Form or appearance of a diamond; i.e.: whether the diamond is round,
Emerald shape — A rectangular or square-shaped cut-cornered diamond. A form of step cutting, this cut is favored for diamonds and emeralds, as well as many other stones, when the principle purpose is to enhance color rather than brilliancy. It is also sometimes used to emphasize the absence of color in diamonds.
Step cut — With rows of facets that resemble the steps of a staircase. The emerald cut and the baguette are examples of the step cut.
Fancy Cut — A diamond cut other than round — such as baguette, emerald, pear, marquise, square, oval, heart, etc.
Marquise shape — A double-pointed, boat-shaped stone that is long and thin with gently curved sides coming to a point on either end. Marquise is part of the brilliant-cut family; ideally cut it has 58 facets.
Pear shape — Term used to describe any diamond whose girdle outline resembles a pear shape. Ideally cut pear shapes have 58 facets.
Trillion shape — Is a triangular-shaped diamond with 50 facets. Trillions are commonly used as side-stones.
Mixed-cut — This cut has both step-cut and brilliant-cut facets. Mixed cuts combine the beauty of the emerald cut with the sparkle of the brilliant cut.
Radiant cut — A rectangular or square shaped diamond with step-cut and scissor-cut on the crown, and a brilliant-cut on the pavilion.
Princess cut — A square or sometimes rectangular-shaped modified brilliant-cut diamond.