G. Allan Jewelers
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706 2nd Ave S.  Suite 268 Baker Center    Minneapolis MN  55402          612.339.5441       Hours M-F 10am-4pm​

Buying Your Perfect Diamond
Making a diamond purchase is personal and can seem daunting.  Understanding the diamond grading system will make your decision more personal and start you down the path. We are here to make that decision easy, fun and a memory to last a lifetime.

Most people refer to the cut of a diamond as the shape: round, oval, pear, marquise, etc. In gemological terms the "cut" actually means the proportioning of the diamond. Each shape has an ideal proportion, a combination of width, depth and precise faceting which maximizes the way light reacts within the diamond. A diamond cut too shallow or too deep will lose light out the bottom or sides. In a properly cut diamond, light entering through the top will internally bounce off the facets and reflect back out the top to your eyes.

Some terms often used to describe this light are:

Brightness: the light reflected from a diamond

Fire: the multiple colors seen emanating from a diamond

Scintillation: the amount of sparkle


Diamond terminology can be confusing. Case in point: COLOR. This refers to the LACK of body color in a diamond. The more colorless a diamond is, the better it can reflect all the colors of the rainbow without distortion.

The diamond color grading scale starts with "D" and continues down the alphabet as is picks up more color. A "D" color diamond is considered colorless while a "Z" color diamond is said to have dark color and will display an obvious yellow-brownish tint.

In broader terms, color can be grouped into categories:
  • D-F colorless
  • G-J near colorless
  • K-M faint color
  • S-Z light color

Diamonds are formed deep in the earth under extreme heat and pressure. Throughout this process, a diamond develops inclusions or characteristics (think blemish) that are all a unique result of diamond formation. The color, placement, size and number of the inclusions will determine the clarity grade. Light can not pass undistorted through an inclusion so it stands to reason that the fewer the inclusions, the higher the value of the diamond.

GIA clarity scale is as follows:
  • Flawless / Internally Flawless
  • ​VVS1 and VVS2 - very very slightly included
  • VS1 and VS2 - very slightly included
  • SI1, SI2, SI3 - slightly included
  • I1, I2, I3 - included

Grading is based on 10x magnification. Although there are exceptions, your eye without magnification will likely only see inclusions in diamonds graded as "included".


Carat refers to the weight of a diamond. One carat equals 200 milligrams in metric weight. A carat can be further broken down into portions or "points". One carat equals 100 points. So a half carat (.50ct) equals 50 points, a quarter carat (.25ct) equals 25 points, etc.

Yes, carat weight definitely factors into diamond pricing. The larger the diamond, the higher the price. However, pricing is not linear. Two .50ct diamonds equal 1.00ct total weight, but they cost far less than one single diamond that weighs 1.00ct.

The 4 Cs are a great way to compare diamonds and to know where you place priorities. Keep in mind that the bottom line is how the diamond looks to your eyes. Grading is an educated opinion. The beauty comes in seeing the diamond sparkle and dance, something you can only see when you visit us in person.

Let's begin to make those memories come true!