January 02, 2020

If you’re a gem gal, or have done some diamond shopping, you’ve probably heard of the 4 c’s: cut, clarity, color, and carat weight. These are the 4 elements that determine diamond quality. Today’s blog is all about the unsung hero, and the single most important factor in determining a diamond’s overall beauty and brilliance:cut.

What Does Diamond 'Cut' Mean?

Diamond cut refers to how well a diamond is cut and polished. It’s the most complex ‘C’ and the least easy to “see” but is what truly gives diamonds their light-catching lustre. Cut relates specifically to round brilliant diamonds – the most popular diamond shape made.

The GIA (Gemological Institute of America) evaluates the cut of round brilliant diamonds based on seven different factors:

Brilliance:the brightness of white light that’s reflected out of the diamond.

Fire:the amount of colored light that’s reflected out of the stone. 

Scintillation:the flashes of sparkle when light moves across a diamond’s facets.

Durability & Weight Ratio:how well the diamond is designed for durability and optimal weight.

Polish:the shine of the diamond’s surface.

Symmetry and proportion:symmetrical facets and proportional design.

A well-cut diamond is luminous – it radiates brilliance, fire, and scintillation. A poorly cut diamond, on the other hand, doesn’t reflect light properly and appears dull. Even if a ring has excellent color and clarity, if the cut is poor, the stone will appear drab and lifeless.

The Other Three 3 C's

The three other factors in evaluating the quality of white diamonds are:

Color:how white or colorless a diamond appears. Color is graded from D (most colorless) to Z (noticeable brown or yellow tint) by the GIA.

Clarity:the level of blemishes or inclusions in the diamond. The GIA rates diamond clarity from FL (flawless) to I3 (noticeable inclusions to the naked eye).

Carat Weight:the weight of the diamond (not related to diamond size as many people believe!).

Cut vs Shape

Ok here’s where it gets tricky. While many people use these terms interchangeably, ‘cut’ and ‘shape’ actually mean totally different things. Diamond shape refers to the outline (rectangular, round, pear-shaped) of the diamond whereas cut relates to less obvious elements like proportion, facets, and polish.

So, even though diamond shapes have names like princess cut, emerald cut, round cut, and pear cut, those names are still referring to diamond shapes, not diamond cut. Not confusing at all, right!

How Cut Affects Sparkle

Sparkle is determined by a diamond’s ability to take in light, then reflect it back out to the spectator. The more light reflected through a diamond’s facets, the sparklier it will appear.

This is where cut comes in – a well cut diamond allows light to exit through the top, giving off a brilliant, multifaceted shine towards the spectator. Poorly cut diamonds, on the other hand, allow light to escape out the sides and bottom, creating a dull, lacklustre finish.

Diamond Cuts - Proportion

One of the most important factors of diamond cut is proportion. Proportion refers to the ratio between different sections of the diamond (see image below).  

Gemologists measure these sections to help determine a diamond’s cut quality, and ultimately, it’s level of brilliance, fire, and sparkle. A well-cut diamond has the optimum ratio between the table, width, and depth to allow light to reflect out of the table (top) rather than out the sides or bottom.

How Diamond Cuts Differ

You can see in the image below how a diamond with the same shape can differ in proportion, angles, and symmetry. All these elements affect how light will reflect out of the stone (and how sparkly it will appear).

Shallow diamond

In a too shallow diamond, light exits through the bottom of the diamond, making the stone appear dull.

Deep Diamond

A too-deep cut diamond cause light to exit through the sides, creating a dull, lackluster look.

Ideal Cut

A well-cut diamond allows light to reflect through the top of the stone, creating a brilliant, luminous looking diamond.

Diamond Cut Grades

The GIA grades diamond cuts from excellent to poor:

Excellent:these diamonds have the highest level of fire and brilliance. 

Very Good:to the naked eye, these diamonds are just as sparkly as the excellent cut grade diamonds and considered very good diamonds by the trade.

Good:still a beautiful diamond, this cut grade reflects less light but still sparkle and shines.

Fair:these diamonds allow light to exit through the bottom/sides of the stone so usually appear dull with minimal sparkle.

Poor:this cut grade has next to no sparkle – all light exits through the sides/bottom of the diamond.

How We Choose Diamond Cuts At Gem Breakfast

When it comes to clear white diamonds, we try to only choose stones with an excellent or very good diamond cut grade. And if it’s a matter of getting the most beautiful diamond for a budget, we always prioritize a high cut grade over clarity or color.  

“Most people looking for white diamonds focus on a high color or clarity grade. What they don’t know, is that to jewelers, the most important factor is how well cut the stone is! You can’t see the cut quality with the naked eye, but it is truly what makes the diamond beautiful to the naked eye. Somewhat of an oxymoron but that's why cut is so important.

When I’m showing white diamonds to people, I sometimes don’t disclose the grading right away.

It’s kind of a fun game - I let them pick the stones that are most visually appealing to them. And almost always, they end up picking the stone with the highest cut grade. And that’s because it is always the most shimmering, sparkly stone in the pile.”        

– Catherine, Gem Breakfast Founder

Pro-tip:well-cut diamonds can camouflage lower color and clarity grades. So, if you're looking for great value in a good diamond, we recommend you optimize for cut and be willing to compromise on the other two C's (color & clarity) to hit a specific budget.

Shop Gem Breakfast

Gem Breakfast Bespoke Ring Cassidy Asscher Cut Morganite & Diamond Ring

Gem Breakfast Bespoke Ring Bella Old European Cut Diamond Ring in Peach Gold

Gem Breakfast Bespoke Ring 6 / 18k Yellow Gold Men's 4mm Comfort Fit Band


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