Diamond Cut

Facets and light

When balancing the many characteristics diamonds have, the quality of the cut is a diamond’s most important attribute. The quality of the cut often has the strongest influence on a diamond’s allure and beauty.

The quality of the diamond cut is measured by the balance of all of its measurements to produce the most light from the top of a stone. If a diamond is too shallow, the light will be lost through the bottom of the stone. If it’s too deep, the light will fall through the sides.

A diamond’s cut quality can impact the visual look of its size, color, and most importantly the way it sparkles for the wearer. At Mark Peter’s, we help you find the balance of cut quality along with carat weight and color to so that you choose the perfect diamond.

GIA® Cut Grades


Ideal Cut

A very limited number of stones. Roughly the top 5% of stones will reach this level of perfection. A “Ideal Cut” diamond will reflect and shine nearly all of the light that enters it.

Very Good Cut

This diamond sits at the top 15% of the quality cut scale. This is a beautiful stone, but the light pattern will be very slightly under Ideal Cut diamonds.

Good Cut

This diamond accounts for 25% of the diamond market based on their quality of cuts. These diamonds reflect a majority of the light that enters them but will dance less for the eyes than an Ideal or Very Good Cut.

Fair Cut

A quality diamond, but not as brilliant as a Good. A Fair can mean that the cutter worked to maximize carat weight or to avoid inclusions.

Slightly Included (SI1/SI2)

Imperfections are visible without 10x magnification. In some cases, they are visible to the naked eye, depending on placement and size. The greatest price drop occurs between SI1 to the VS range of clarity.

Included (I1)

Inclusions visible to the naked eye. The scale continues down towards I2 / I3, but we do not generally carry these at Mark Peter's Diamond Designs or suggest them for our buyers.

Poor Cut

These diamonds are significantly out of proportion with much too deep or too shallow cuts. This quality will cause the diamonds to lose light either out of the sides or the bottom of the stone and reduce the diamond’s sparkle.

Diamond Shapes


Brilliant And Step-Cut Diamonds

Diamonds that are Brilliant have facets that radiate from the center due to their triangular and kit shapes. Whereas Step-Cuts are made from long and skinny stepped facets that are made to produce a house of mirrors effect.

Round Brilliant

The most popular shape for diamond engagement rings is also the most available shape of stone on the market. If you’re looking for very specific characteristics, often the most options will be found in Round Brilliant diamonds. Over many years, the Round Brilliant has been perfected with a focus on producing the most sparkling and brilliant stones possible.


Known for showing increased brilliance thanks to large facets and rounded edges. The Brilliant diamond can sometimes be difficult to distinguish between others, depending on how obvious the curves along each edge are.


With rectangular facets and a large, open table, this Emerald isn’t uniform in length-width ratio. Each stone is slightly different in shape/size. They can be longer, shorter, or even square. Pay attention to clarity. The large open table draws attention to this characteristic, often with SI2 or worse stones, it can be easy to look through the table to find inclusions.


Known for sharp, pointed corners and beautiful fiery brilliance. While the shape is generally square, this characteristic will vary from stone to stone.


Very similar to an emerald but it is much more square. The length to width ratio on an Asscher diamond will be close to 1.


Generally long and skinny with a focus on making the stone look as large as possible for the given carat weight. It will also make one’s fingers look even longer and skinnier.


This can be more square or more rectangular. You can distinguish them by their trimmed corners.


These stones vary in shapes of a teardrop. Like the marquise, this Brilliant-Cut Diamond often makes one’s fingers look longer and slimmer. Avoid a Pear that features a strong “bow-tie” effect when looking through the top of the stone.


A distinctive choice using the exact shape we use to symbolize love.

Follow us on Facebook, Instagram, YouTube, and Pinterest. Also, feel free to Contact Us anytime to set up an appointment.