Engagement Ring Guide: How To Choose A Diamond | Brilliant Earth
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choose the right

Select a Shape

Round Diamonds

When selecting a diamond, your first priority is usually to choose a shape. If you’re unsure of what shape to choose, it may be helpful to know this: round diamonds are by far the most popular choice due to their incredible brilliance, fire, and light performance. Round brilliant diamonds make up about three-quarters of all diamond purchases, and offer maximum sparkle.

Fancy Shapes

Princess diamonds feature an angular, contemporary beauty that looks gorgeous in classic and geometric settings, and are second in popularity, offering the brilliance of a round brilliant diamond at a lower price. Cushion diamonds are an ideal choice for vintage-inspired settings, and radiant diamonds are a stunning alternative to princess and cushion diamonds for those preferring a rectangular shape. Asscher and emerald diamonds are step-cut, for a sleek, elegant appearance. They emit less fire or sparkle than round diamonds but are more transparent. Marquise, oval, and pear-shaped diamonds are more distinctive shapes, and help fingers look long and slender due to their elongated appearance. Heart-shaped diamonds express your sentiment with a flourish and are often favored by die-hard romantics. Marquise or pear-shaped diamonds may appear to be larger, given that more of the stone shows from the top view (looking down on the diamond).

Based on the laws of supply and demand, you can currently save up to 40 percent by selecting a non-round diamond. At Brilliant Earth, we offer 10 classic diamond shapes. Please contact us for other diamond shapes, such as trillions, baguettes, and half-moons.

shape your future

most popular setting

Willow Diamond Ring

Willow diamond ring

by the numbers

75% of diamond engagement rings feature a round center stone.

fun fact

The modern round brilliant cut was invented in 1900.

shop round diamonds

Choose a Size

The final set of considerations involves two main factors: the size of your gem and its quality. When selecting your perfect diamond, determine what is most important to you within your given budget – size, quality, or a tradeoff between the two. Many people start with size, as this is the most visually apparent aspect of a diamond. Keep in mind that a carat is actually a unit of weight, but it can be used as an approximation for the size of a diamond. You may find the measurements of a diamond another useful indication of the actual dimensions, as seen face up.

The size of a gem compared to a dime

learn about quality


The most important quality characteristic of a round brilliant diamond is the cut, which impacts the brilliance, fire, and scintillation of the diamond. If the workmanship and cut of a diamond are poor, the diamond will look dull and lifeless. With round brilliant diamonds, the cut is easy to assess because it is formally graded by independent diamond laboratories. For other diamond shapes, the cut is much more subjective. Cut grades, if given, are more arbitrary. For engagement rings, we typically recommend round brilliant diamonds with a cut grade of very good, ideal, or super ideal (also known as hearts and arrows). Choosing a high cut grade maximizes the beauty of a diamond for a given carat weight.

Cut Scale


The other main quality characteristics to decide are the color and clarity of your diamond. Although individuals vary in their ability to observe color differences, most people prefer a colorless or white diamond, or at least a color that is not very detectable to the untrained eye. With engagement rings, the most common color grade selection for the center diamond is F-H color.

Color Scale


Clarity is usually the characteristic determined last, given it has the least impact on a diamond’s appearance. Some diamonds graded “SI2” or “SI1” do have visible inclusions, but at Brilliant Earth we will contact you if the diamond you have chosen has an inclusion that we can see with the naked eye. Many Brilliant Earth customers choose the “VS2” or “SI1” clarity grades for the center diamond of their engagement ring. A few customers for whom clarity is important go as high as the “IF” or the “VVS” clarity grades.


10x magnification

final thoughts

Assortment of loose diamonds in different shapes.

It is always best to choose a diamond that comes with an independent diamond grading certificate from a recognized gemological laboratory. An independent assessment ensures you are getting exactly what you are paying for. Keep in mind that evaluations by the European Gemological Laboratory, or EGL, are much more lenient compared with evaluations by other laboratories. We recommend striking a balance between a diamond’s size (as represented by carat weight) and its quality (or its cut, color, and clarity).