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The GIA grades for round cut engagement ring diamonds are:

ExcellentVery GoodGoodFairPoor

* Interestingly, most diamonds sold in America would grade below GIA’s Good category. This is especially true of diamonds offered at supposed wholesale prices.

Caution! Be very careful not to confuse jewelers descriptive adjectives as actual cut grades. For instance, a jeweler may refer to a diamond as a “very good cut”, and yet have no idea if it would qualify for a GIA Very Good cut grade. A buyer needs to ask for a Sarin machine generated GIA report that grades the diamond as Very Good before assuming an actual cut grade.

Rule: When any jeweler gives a quote, pay attention if the cut grade is also given. If not, don’t buy there. Anyone who leaves out this grade either doesn’t know what they are doing or is withholding crucial information you need to compare prices. Such omissions always mean that the cut grade of the diamond they have is Fair or Poor. (That’s why they don’t disclose it)!

Ideal Cut

Exceptionally cut diamonds receive a grade above all others designated Ideal Cut. Ideal Cut is defined with more strict requirements for proportions and finish than any other diamond, which makes them extremely brilliant, and rare.

In a brilliant-cut round diamond, the closer the diamond adheres to the Ideal standards, the more sparkly it will be and the more expensive it will be. The reasons for the expense are two-fold. To get an Ideal cut, more of the original diamond crystal is cut away; therefore, a diamond cutter must decide whether to go for maximum beauty or maximum weight. A diamond cutter will probably cut the diamond he can sell the quickest. Even though there is a demand for both beauty and weight, it is surprisingly less for beauty.

The other reason Ideal cut and better cut diamonds are more expensive is that greater time and care must be taken to ensure symmetry (how well one side mirrors the other side) and polish (the quality of finish) are excellently done. A diamond with superior polish and symmetry will be much brighter than one that is poor, fair or just good. When you see an Ideal cut compared to other diamonds, this difference is remarkable and unmistakable.

Rule: All diamonds have some brilliance, but an Ideal Cut diamond will offer the maximum play of light and sparkle

Hearts and Arrows Ideal Cuts

For the purists among us, one last area of cut bears mentioning. It’s called “Hearts and Arrows” Ideal Cut, and it’s the creme-de-la-creme of diamond cuts.

Hearts and Arrows (H&A) Ideals are perfectly (eccentrically so) symmetrical Ideal Cuts. These cuts show a clear pattern of eight heart-shaped reflections when the bottom (pavilion) side of a round brilliant diamond is viewed under a special viewer called a “Fire Scope”. When viewed face up on a Fire Scope, a pattern of eight long reflections that look like arrows are visible. Hence, the “Hearts and Arrows” designation. The result is incredibly stunning. Only a very few cutters worldwide have the ability to produce H&A Ideal Cuts. Diamonds cut to this standard are often marketed under brand names drawing attention to the eight-star pattern that a true H&A Ideal Cut diamond produces under a Fire Scope.

Rule: Always ask about the GIA cut grade on any diamond you are considering buying. Also ask the jeweler to show you on a Sarin machine how they knows it’s that particular grade, including exact percentages of the top, bottom, and all angle measurements. Be especially wary if the jeweler claims that most or all of their diamonds are Ideal, and can’t show you a machine generated report stating Ideal.