What are Round Brilliant Cut Diamonds?

September 17, 2023

The round brilliant is the most classic diamond shape revered for its unmatched fire and brilliance. Its concentric circles of facets have been precision crafted for centuries to optimally interact with light. This guide will cover everything you need to know about round brilliant diamonds including cutting style, grading factors, settings, comparisons and FAQs.

Brief History of the Round Brilliant Diamond

Round diamonds have been fashioned since antiquity. But the modern round brilliant evolved slowly through centuries of experimentation with faceting arrangements.

In 1919, mathematician Marcel Tolkowsky published calculated proportions to optimize diamond brilliance and fire through precise faceting. His calculations formed the basis for ideal cut standards today.

Advancements in the 20th century enabled the crafting of round diamonds with excellent symmetry, polish and light performance. The traditional round brilliant has reigned supreme as “the classic” ever since.

Round Brilliant Cut Facets and Proportions

The round brilliant is defined by 58 precisely aligned facets and careful attention to symmetry:

  • Circular outline
  • 58 brilliant-style facets
  • Table aligned with girdle
  • Equidistant crown and pavilion facets
  • Shallow crown, deep pavilion
  • Ideal table 53% - 58% of diameter
  • Total depth between 59% - 62.5%

Maintaining proper crown and pavilion angles is key for maximizing brilliance and dispersion (rainbow sparkle). An ideal cut will have 41.5 degree crown angles and 40.75 pavilion angle.

Grading Factors for Round Diamonds

Round brilliant diamonds are graded using the same 4Cs characteristics as all diamond shapes:

  • Cut – Well-cut rounds have Excellent or Very Good cut grades, ideal scope images, light performance, and precision crafting.
  • Clarity – VS2, SI1 clarity is eye-clean and maximizes sparkle and affordability.
  • Color – Colorless to near colorless grades D-J face up bright white and provide value.
  • Carat – 0.50 to 1.5 carat, with 1 ct considered the “magic” size.

With rounds, always prioritize cut quality, symmetry and polish over carat weight to maximize beauty and light performance.

Round Diamond Settings

Round diamonds pair elegantly with both modern and traditional settings:

  • Solitaire – Iconic 4 or 6 prong solitaire setting.
  • Side stones – Mix with baguettes, princess cuts or trillion diamonds.
  • Three stone – Stunning as centerpiece with trapezoid diamond sides.
  • Halo setting – Enhance size with a micropavé halo frame.
  • Eternity band – Pair with pavé, channel or bezel set bands.

The round diamond works with virtually any ring style. Keep the setting streamlined to avoid distracting from the stone.

Round Diamond Prices

Price ranges for a 1 carat round diamond:

  • D color, IF clarity, Excellent cut - $9,500
  • G color, VS2 clarity, Very Good cut - $5,500
  • J color, SI1 clarity, Good cut - $3,400

Rounds typically sell at a 10-20% premium over fancy shape diamonds of similar carat, clarity and color. Their craftsmanship warrants the pricing difference.

Round Brilliant Cut FAQs

How does brilliance compare to other diamond shapes?

The ideal round brilliant reflects light back through the crown with the highest brilliance and fire of any shape when optimally cut.

Should I choose GIA Excellent or AGS 0 Ideal cut?

Both signify excellent light performance. AGS has stricter standards but also costs more. Optimal GIA Excellent rounds offer exceptional value.

Can a round diamond ever have a bow tie?

Rarely, poorly cut rounds may show an undesirable dark bow tie effect in the center. Avoid rounds with strong, dark bow ties.

Do rounds show more color than princess cuts?

No. Near colorless rounds and princess cuts face up similarly bright. Hues are more apparent in emerald cuts. Rounds hide color well.

Should I buy the largest possible round diamond?

No, prioritizing carat weight over cut can reduce beauty. Choose the optimal combination of cut, clarity and size based on your budget.

For over a century, the round brilliant has remained the most optically stunning and sought-after diamond shape. When expertly cut and proportioned, round diamonds deliver unmatched brilliance, life, and allure.

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