Round Brilliant Cut Diamond Buying Guide: What to Know

Round brilliant cut diamonds are jewellery's biggest stars. Their amazing sparkle and timeless style are endlessly appealing. If you're searching for the perfect round brilliant, this Round Brilliant Cut Diamond Buying Guide will help. Niche Diamonds will help you find the perfect round brilliant for your dream jewellery piece.

What Is a Round Brilliant Cut Diamond?

The search for the perfectly brilliant diamond goes back centuries. Early cuts like the Old Mine and Old European had their charm, but they lacked the scientific precision we have today. In 1919, Marcel Tolkowsky developed a mathematical model of the ideal round brilliant. It was designed for maximum light and unmatched sparkle.

A round brilliant diamond is all about symmetry and precision. Its key facets – the crown, pavilion, table, and culet – work together to control how light reflects. The proportions and angles of these facets determine the diamond's brilliance, fire, and scintillation.

Cut is the most important factor for a round brilliant beauty. A well-cut diamond dances with light and dazzles your eye with every move. A poorly cut diamond looks dull and lifeless. When choosing a round brilliant, always put cut quality first.

How To Evaluate a Round Brilliant Diamond


A round brilliant cut grade is its most important feature. The Gemological Institute of America (GIA) uses a scale from Excellent to Poor. Ideal proportions, specific table percentages, and perfect crown/pavilion angles work together to trap light inside the diamond and send it dazzling back to your eye. Beyond the basic grade, look at symmetry (how precisely aligned the facets are) and polish (how smooth the surface is).


Round brilliants are fantastic at hiding slight colour tints. The colour scale goes from D (colourless) to Z (noticeably yellow). Near-colourless grades (G-J) can appear just as white to the eye as D-F diamonds, making them a smart way to stretch your budget. Remember, a great cut can minimise any hint of colour.


Flaws, called inclusions, are natural in diamonds. Grades go from Flawless (FL) to Included (I3).  Eye-clean diamonds mean you can't see any flaws with the naked eye. Since round brilliants sparkle so much, you can often choose a lower clarity grade and still have a stunning, flawless-looking diamond.


The carat of a diamond is a measure of its weight, and it affects the price of the diamond. However, the way a diamond is cut determines how large it appears to the naked eye. So, even if two diamonds have the same carat weight, the one with a better cut will give the illusion of being larger because it reflects light better and has more sparkle. 

Prices jump at whole carats (1.00 ct, 2.00 ct, etc.), so picking a slightly smaller stone (like a 0.90 ct) can maximise your budget while still giving you a beautiful look.

Choosing the Right Setting for Your Round Brilliant Diamond

Solitaire Settings

classic solitaire puts all eyes on your round brilliant diamond. The simple design lets your diamond's sparkle shine. Variations like cathedral settings (where the band arches up) or sleek bezels offer different styles. Think about metal types too – platinum is timeless, while yellow or rose gold adds warmth.

Halo Settings

Want a bigger look for your diamond? Halos do the trick. They frame your centre stone in a ring of smaller diamonds, boosting its size and sparkle. Choose from single halos, extra-dramatic double halos, or even hidden halos tucked beneath the centre stone.

Side Stone Settings

Three-stone rings are a classic, pairing your round brilliant with side diamonds for extra sparkle.  Pavé settings line the band with tiny, shimmering diamonds, while channel settings give a clean, modern look. Get creative with side stone shapes like tapered baguettes and other fancy cuts.

Additional Factors to Consider

Fluorescence can sometimes make diamonds appear slightly hazy in sunlight, so check your diamond's certificate for its fluorescence level. Trustworthy grading reports are important – look for GIA or AGS certificates. 

Lab-grown diamonds offer the same beauty as natural diamonds, often at a lower price, and appeal to eco-conscious buyers.

You Can Never Go Wrong With a Round Brilliant Cut Diamond

Remember that the most important factor is always the cut. A well-cut diamond will sparkle and catch the eye from across the room. When exploring diamonds, make cut quality your top priority for the most dazzling effect. 

A great setting will also showcase your diamond's brilliance, so take time to find one that matches your style.