Good Diamonds vs. Bad Diamonds, Emphasis on Cut

bad diamonds

You’ll Want This Beautiful Diamond to Keep Sparkling Even When it gets Dirty. Proper Cut is the Key.

The Four C’s Gone Bad – Diamond Cut

As a Santa Barbara Jeweler, I had the unhappy task of explaining to Marly and John, a nice young couple, why that center diamond they got online with the great appraisal certificate looked so lackluster.

I didn’t like saying it and they didn’t like hearing that it lacked the dispersion or sparkle necessary for daily wear.

Buying bad diamonds is a tragic event in any young couple’s love life. This is the first in a series of blogs written to help you avoid buying bad diamonds.

With Great Color and Clarity it’s Still a Bad Diamond With Bad Cut

Most of you have already heard of the 4 C’s when referring to diamonds: Color, Clarity, Cut, and Carat Weight. John had, but he was missing a little bit of the down low on cut. I’m going to talk about one of the most overlooked, yet most important C: cut.

Good diamonds vs. Bad Diamonds

The Naked Eye Can’t See the Tiny Details of Cut Quality.

Unlike the other three C’s that are measured by carat weight, color, or clarity grade, cut isn’t so easy to classify. Unless you’re an expert, you can’t just throw a diamond on a scale or look at it under magnification to discern its quality.

And seriously, two experts might not agree on its value! Before we get into how to go about telling a good cut diamond from a bad cut diamond, let’s first review some facts about diamonds.

Shape vs. Cut, Yeah, You Should Read this Part

Names and images of shapes of diamonds

Different Shapes of Diamonds

Cut is different than shape. Shape is the basic form or outline of a stone. Examples of different shapes are: round, square, marquise, and triangular. Theses are all shapes.

Cut refers to the geometric proportions of a given shape.

Round shaped diamonds come in many different cuts. Despite what I just told you, you will still hear the words “cut” and “shape” used interchangeably. Don’t worry. Just know that a “round cut” diamond is round in shape.

Parts of a Diamond, What Those Angles Are Called

The flat top of a diamond is called the table. The thin center perimeter of the stone is the girdle. The section between the table and the girdle is called the crown.

The section between the girdle and culet (the point at the bottom) is called the pavilion.

Facet Names of Parts of the Diamond

Names of the Parts of the Diamond

All the flat planes on a diamond are called facets. The table is largest facet. The culet is the smallest.

Depending on how the stone is cut, round diamonds will have different numbers of facets.

In a good diamond, all the facets are completely smooth and polished.

Dimensions: Do I Have to Understand This Stuff? (Yeah)

All the different dimensions of diamonds are measured in millimeters. These measurements would include diameter, width, and height. These measurements and the angles and the ratios of the different parts of a diamond to each other are what are called proportion.

All other C’s being equal, a stone cut with ideal proportions or near ideal will shine and stand out more than a poorly cut one.

Ideal Cut: Do I Have to Buy an Ideal Cut?

Experts often refer to “ideal” cut diamonds. These are stones deemed to have been cut using agreed upon proportions to maximize their shine and sparkle.

A Hearts and Arrows Cut Diamond Under Magnification

A Hearts and Arrows Cut Diamond Under Magnification

You’re probably wondering why all diamonds aren’t cut “ideally?” Oftentimes, it’s just not possible due to what the diamond cutter has to work with.

The rough stone might not present enough material to allow for an ideal cut. There could be a pretty big carbon spot that needs to be cut away.

There are plenty of gorgeous diamonds that are near ideal cuts that look fabulous. You do not have to have an ideal cut or one of the labeled diamond cuts like the Tolkowski cut or Hearts and Arrows or other patented cut styles to have a lively and sparkly diamond. But it helps to have one of these great cut styles.

Diamond cutter's wheel

A Diamond Cutter at their Craft

Why Would Someone Cut a Diamond Badly?

Another reason for poorly cut diamonds is due to diamond cutters wanting/needing to preserve as much stone weight as possible for the maximum final diamond weight.

As an example, a particular diamond might weigh .90 carats if it was cut ideally. Diamonds weighing 1 carat or more fetch a more premium price. The cutter might be tempted / or told to, facet the diamond a bit differently to preserve the extra weight, making it a more expensive diamond by weight.

Reflection, Refraction, Dispersion, Words You Need to Understand

Light bouncing off the surface of a diamond is called reflection.

Light entering the stone and bouncing off an interior wall is called refraction.

The light exiting the diamond is called dispersion. As you might have guessed the more light refracting from inside the diamond and dispersing from the table, the better.

Light Dispersion and Light Refraction Chart

Light Dispersion and Light Refraction Chart

Good diamonds refract and disperse lots of light. Bad diamonds don’t. They just reflect light, which any piece of clean piece of glass can do.

You need to look beyond mere reflection. The reason good refraction and dispersion are so important in your chosen diamond is because when you wear your diamond every day it will get dirty.

A well cut diamond will continue to sparkle with less light coming in. A bad diamond when it gets dirty will sit there like a piece of dull glass. A bad diamond might work OK in a pendant that stays relatively clean, but your ring diamond will get lotion, soap scum and just life dirt on it.

If it’s a good diamond, it’ll keep that love sparkle going. If it’s a bad diamond it’ll break your heart.

When you look at a diamond, rock it back and forth to see the light dispersion. The most important light dispersion is what you can see looking down into the table. You’ll also see dispersion of light from those top crown facets.

Once you can tell the difference between light reflection and light refraction, you will be ahead of most first time diamond shoppers.

Fancy Display Lights Can Fool Your Eye When Diamond Shopping

Bright Lights Make Poorly Cut Diamonds Looks Pretty Awesome

Bright Lights Make Poorly Cut Diamonds Looks Pretty Awesome

Poorer quality diamonds can be made to look better than they really are by showing them under the mega-wattage overhead lights of some jewelry stores.

A diamond of  poor quality will not look as good at your office or in your kitchen as it did at the store where you bought it.

For this reason, I recommend examining diamonds in natural light, away from the jewelry store counter brilliance.

Find the Ugly Light to Find Your Good Diamond

Don’t let fancy light and a clean reflection fool your eye. When you are shopping for your diamond, try to look at it away from  the mega-wattage overhead lights of the jewelry store.

Fancy high intensity display light can make the poorest cut diamond refract light like a champion. Take that diamond that you are considering to a more poorly lit part of the room, or a hall, or even the bathroom.

Compare a diamond that has proven nice light refraction next to a candidate diamond. This would be a diamond that you know is awesome, like in a friend’s engagement ring.

Once you are in the ugly light, only a well cut diamond will still give good light dispersion.

How is a Bad Cut Diamond Made?

Most of the time a bad diamond-cut result has to do with the choices the diamond cutter made. He may have had the bad luck of being saddled with big carbon inclusions that were naturally occurring in all the wrong places in the rough diamond crystal. The cutter took the hand he was dealt and made his choices and they didn’t include what would create the most light dispersion.

This Beautifully Cut Diamond Would Probably Sparkle in a Coal Mine!

This Beautifully Cut Diamond Would Probably Sparkle in a Coal Mine!

How You Can Spot a Bad Diamond Cut

A shallow cut diamond may look bigger due to a larger table, but due to all the light escaping out the sides, it lacks the brilliance and fire of a smaller well cut diamond.

Deep cut diamonds often suffer the same fate. They don’t refract light up toward the eye the way a more ideal cut diamond does.

The angles, symmetry, and facets of an ideal cut diamond or near ideal have been skillfully and effectively proportioned to reflect and refract the maximum amount of light. An well cut diamond shines and sparkles and shows fire and brilliance. Poorly cut diamonds don’t.

How to Tell a Well Cut Diamond from a Poorly Cut Diamond

If you’re like John, all the facts, figures, and dimensions on a GIA certificate won’t mean squat to you. I don’t even know what all the ratios and dimensions mean off the top of my head!

Magnifying Loupe and Diamond in Tweezers

Magnifying Loupe for Looking at Diamonds

So what do we do? Assuming two diamonds are the same weight, the same color, and of the same clarity, how do we tell which is better cut? What’s a poor woman (or guy) to do?

Start by examining the two diamonds side by side. Look at them from as many different angles as you can.

Do this with your eye as well as with a loupe. Look straight down through the table. (The flat part on top)

Four Steps to Checking for Good Diamond Cut

Loose diamonds on a black background

Looking at Diamonds Next to Each Other Helps You Differentiate the Ones That Have More Light Dispersion

1. Look at each stone from the side. Look for imperfections, scratches, and chips.

2. Pay attention to the symmetry of the facets. Are they all the same shape the same size or does one look slightly out of proportion to the others?

3. Check the girdle. Make sure it’s perfect all the way around.

4. Check the culet. Make sure it’s not chipped or broken. (Bottom pointy part)

Dispersion, Sparkle and Pizazz – Does That Diamond Sing?

good diamonds vs bad diamonds

This Picture Captures Light Return Amazingly

Finally—and this is most important!—examine the diamond for its natural sparkle! See if one stone shows more color reflection than the other.

Does it seem to have just a little more pizzazz? If it does, chances are it’s a better cut stone.

I care little for anything else. Oh yeah, except color and clarity, but that’s another post! Is the rock I’m looking at a little ball of blazing sunlight or a dull lump of beach glass? I call this the Pizzazz Factor!

A diamond with pizzazz, a good diamond, will sparkle, shine, glitter and glow in cleanliness and dirtiness. (I mean we have lives and are busy and can’t be expected to slavishly clean our diamond ring nightly!) A poorly cut, or bad diamond will break your heart. Or your wallet as John can tell you.

Put Down the Loupe, Use Your Eyes

Three Ring Wedding Set with Inherited Diamonds

Look at How This Diamond Returns Light and it’s in Shadow!

You don’t have a loupe with you in life. How will your diamond look in life, in normal everyday places? In ugly light? Use your naked eye to see the light dispersion from one candidate diamond to another. Let your eye make the final choice.

The diamond you are considering may have great color, and fabulous clarity and a fantastic price, but if the way the stone has been cut is flawed then you’re looking at a bad diamond.

John and Marly’s Excellent Ending

Just so you know John and Marly had a happy ending. They returned their diamond less a restocking fee, which John was happy to pay. They looked at diamonds side by side with me and picked a diamond with a lot of light refraction and dispersion.

The Vaseline Test

We even did the Vaseline test. I rubbed Vaseline on the bottom of each diamond to simulate the life dirt that gets on your diamond.

One diamond sparkled more energetically than the other after the test and it is now on Marly’s hand. She love, love, loves it. In her words. May the diamond you select make your heart and her heart sing!

Calla Gold

A book I recommend is:

DIAMONDS, 3RD EDITION The Antoinette Matlins Buying Guide—How to Select, Buy, Care for & Enjoy Diamonds with Confidence and Knowledge

Antoinette Matlins Excellent Book, "Diamonds" if you Want to Know Everything!

Antoinette Matlins Excellent Book, “Diamonds” if you Want to Know Everything!

About Calla Gold

Calla Gold is a Personal Jeweler and Author who takes pride in working with clients one-on-one to integrate their personal sense of style and taste into custom designed jewelry and repaired jewelry pieces.   Unlike typical Santa Barbara jewelry businesses, Calla Gold has no brick-and-mortar location. Calla Gold comes to you, bringing you the jewelry collection you want to see and collaborating with you to create unique custom jewelry. Calla also works with at-a-distance clients.

10 Comments

  1. Tania on July 1, 2014 at 11:20 am

    Calla,
    This was absolutely eye opening about bad diamonds. Most of the points mentioned on this blog post I had never even heard of!
    This information is absolutely essential for anyone looking into buying a diamond. Great post!

    Tania

    • Calla Gold on July 1, 2014 at 8:00 pm

      Dear Tania,
      I’m so pleased that this data was new to you. I love writing about diamonds, gemstones and jewelry. To have it help someone’s knowledge and protect them in the future is my goal!
      Your Personal Jeweler,
      Calla

  2. Mark Johnson on July 14, 2014 at 9:04 am

    Hi Calla,

    Another wonderful post. It was great to read your post and such a detailed account of diamond cut – so often overlooked by both buyers and sellers. It is astounding to think that a diamond with the same weight, colour and clarity can vary by as much as 40% in value, depending on the cut. There are so many great points to take away here!

    Mark.

    • Calla Gold on July 14, 2014 at 10:05 am

      Hi Mark,
      I’m so pleased you liked the many points and interesting tidbits about diamond cut and what a difference it makes.
      Your Personal Jeweler,
      Calla Gold

  3. Pye on September 16, 2015 at 5:02 am

    Thanks for an interesting read! Curiously, many contemporary jewellers are now looking for more ‘flawed’ gems – which fall down on the traditional measures of clarity or colour and even on cut and making interesting and eye catching pieces with them – I’m thinking of the Polly Waleses and Ruth Tomlinsons of this world. After all, a preference for super clear diamonds, or a lot of fire, or no spotting, might be a cultural trend some are willing to buck (much like the number of brides opting for something other than white wedding dresses).

    Sometimes a ‘compromise’ on colour, for example, going for something more on the cognac spectrum, without a compromise on cut or carat, can produce something truly unique and spectacular. Or even a so called ‘miners cut’ might appeal to some.

    From my perspective, flaws can be beautiful, and part of what makes a piece recognisable, and therefore special. Just like your beloved, that freckle doesn’t mar his or her beauty but rather becomes one of the tokens by which you recognise him or her. A setting that works with a stone in this way can be great – think of those beloved heirloom pieces from the 18th and 19th centuries, when cutting was less precise, open settings were harder to make, and differences in colour or clarity were tolerated; many have a warmth and personality that many a perfect 4Cs modern ring lacks.

    In any case, knowing what you are buying, and the reasons why a gem is why it is, are vital; if you’re going for a rough diamond, you should know it, (and be paying accordingly – though with many a contemporary jeweller, what you ‘save’ on what the market considers an ‘imperfect’ diamond can well be spent on the other side working up an interesting bespoke design). Informed buyers always do better, and are always happier in the end.

    Thanks again for an informative post!

    • Calla Gold on September 16, 2015 at 6:08 am

      Hello Pye,
      You have contributed wonderfully to the conversation about cut. I made an all cognac diamond wedding band with swirls and open elements in rose gold. I just had a chance to visit my client who was wearing it yesterday. She looks so great in it. It is such a unique ring and suits her and shows her to be the kind of person who’ll buck the trend her was and look fantastic doing it.
      About older cuts like miners cuts, I work with them regularly. I prefer to set them in custom vintage styles which I feel sets them off.
      I once took a big kind of ugly looking miner’s cut diamond out of a super simple shiny four prong solitaire setting. This simple sleek setting called for a perfect sparkly stone, and had instead an visibly uneven cut with a couple of eye-visible inclusions.
      I designed a six prongs much engraved vintage style setting. Her diamond looked quirky and older and perfect for the setting.
      It went from the diamond none of the sisters wanted to a source of jealousy to the sister who took it with everyone’s approval. She was of course delighted.
      Sometimes if you have a diamond with a less than great cut you can work with it.
      I took a diamond with a big white line inclusion and set it in a modern setting with an asymmetric bold architectural angular look. On one side of the big line I made the setting shiny, and on the other I made it matte. We highlighted the line inclusion and made it look unique. Her ring is a showstopper.
      I agree with you that you can use diamonds cut with less perfection if you choose well and design to make their unusual attributes work for you.
      Thank you for your kind words about my post and your contribution to the conversation.
      Your Personal Jeweler,
      Calla

  4. Veronica Lilliana on September 25, 2015 at 3:27 pm

    I must say, thank you for going into such detail about this topic. It only confirms that my fiancé did his homework and pretty much mentioned all these points to me when he explained his adventure in finding the perfect diamond for my engagement ring. My round solitaire sparkles so much, especially under dim lighting. He didn’t splurge on carat weight or clarity or color. He took it into account yes, but made sure the CUT was as close to ideal as possible. You can barely tell if a diamond is colorless and has no inclusions. It’s the cut that really makes it shine. I just hope more people really do their homework before they drop down their credit card. I’m passing this info as much as I can. Again, Thanks for the detailed post!

    • Calla Gold on September 26, 2015 at 7:31 am

      Hi Veronica,
      Your fiance really did a great job on selecting your diamond didn’t he? Thank you for explaining his story to you about choosing your diamond. That is very cool. It was my pleasure to drill down here. Most of the time my thoughts, opinions and story remain in my head or come out when chatting with clients, but this was bursting to be shared as a drill down down load. I’m really pleased that you like it.
      Enjoy that wonderful man of yours and your happy married life.
      Your Personal Jeweler,
      Calla

  5. Bob Moore on December 22, 2018 at 6:11 am

    I am concerned about a jeweler switching out a good diamond for a bad one when you
    take your ring in for cleaning or resetting. How can we be sure we are being treated fairly.

    • Calla Gold on December 22, 2018 at 7:21 am

      Hello Bob,
      That is a good question. I actually wrote an entire blog about it:
      https://www.callagold.com/diamonds/how-to-avoid-diamond-switching/
      But I’d say that I have never met anyone who ever had a diamond switched. I’ve seen TV shows about it. All the jewelers I know who either design jewelry as well as sell it or who are experts in some aspect, like antique jewelry etc are very worthy of trust.
      Read about getting to know the fingerprint of your diamond and then you’ll be confident when you see your diamond, after repairs have been done.
      Your Personal Jeweler,
      Calla

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