How to Evaluate a Diamond Engagement Ring

If you haven’t read the The Strategist’s Guide to Buying a Diamond Engagement Ring yet you should probably do that before reading this.

Get Smart on Diamonds

If our objective is to buy a high-value diamond within your budget, then one of your most critical tactics is to get smart on diamonds. This article covers the properties that have the biggest impact on how diamonds look to your naked eye. Since paying for features you can’t see is a waste of money, each section below discusses where the thresholds are for these visible properties and how to maximize value while staying within your budget.

The “4 Cs” Are Marketing

Despite the marketing half-truths I discuss in the strategy article, the 4 Cs – Cut, Clarity, Color, and Carat – are real variables to consider when purchasing a diamond. But we need to alter the 4 Cs and add a few more variables to the equation as well: Certification, Ring (Style, Setting, Material & Color), Cut, Shape, Clarity, Color, and Carat are the most important factors for accomplishing our objective.

We’ll also add a lot more nuance to the 4Cs than the over-simplified sales pitch you’ll get from your local jeweler.

Don’t panic. None of this is really that complicated, it’s just different than what you may have been told by the diamond industry. And I’ll give you some clear guardrails at the end to keep you on track.


Certification affects nearly every one of the other factors of a diamond so I need to address the basics now so that some of the specifics make more sense as they come up below.

If I handed you a clear stone that sparkled beautifully and told you that it was 3 carat flawless, colorless, perfectly-cut diamond worth over $200,000, how would you know I was telling you the truth?

What do these words (flawless, colorless, perfectly cut) even mean? This is the problem that certifiers help address. Certifiers give us a common vocabulary so that we can talk consistently about the qualities of a diamond.

So it’s absolutely critical that any diamond you buy be certified. But not all certifiers are the same. In fact, some are basically fraudulent and most are just bad at what they do.

Shady diamond wholesalers will work with certain certifiers to basically lie about the quality of their diamonds so that they can sell low-quality product at a higher price. Other certifiers have the major problem of not being able to consistently certify a single diamond the same way twice.

So it’s not only critical that diamonds be certified, but it’s critical that they be certified by someone who has a trusted brand.

Finally, it’s a no-brainer that the certifier be a third party – a diamond retailer shouldn’t be certifying their own diamonds. If the seller is also the certifier, they have a perverse incentive of maybe wanting to fudge how good their product is. It’s better to avoid companies that have such terrible moral hazards – even if they have a generally trusted brand.

As of late 2017, there are only two certifiers who meet these criteria. The very best in the industry is GIA. If you can’t get a GIA diamond for some reason, then only settle for an AGS diamond.

Bottom Line: Diamonds you’re considering must be certified by a reputable 3rd party, preferably GIA.

Ring Style, Setting, Material & Color

Style & Setting

Before we dive too much further into diamonds, it’s important to know what’s going to be around the diamond. Is the diamond going to be a solitaire – a single stone that’s the center of attention – or do you want something more complex?

There are many different styles of engagement rings and over a dozen broad buckets. The simplest ring style is the solitaire diamond, set in place with prongs. This classic look draws all of the viewers attention to the diamond and the small the prongs maximizes how much light enters the diamond.

But there’s also a huge desire and market for more complex rings styles. Halos are popular for some because they give the appearance from a distance that the ring is substantially larger than it actually is. Pavé and channel rings are two slightly different styles where small diamonds wrap around part (or sometimes all) of the band. Three-stone rings are exactly what they sound like: a single stone in the center with two smaller, sometimes non-diamond stones, on each side.

I don’t have the room in this article to go into the detail of each style so learn more with this style guide.

Ring complexity increases costs in several ways: they are more expensive at the time of purchase, they can be costly to resize, they cost more to insure, and complexity increases the odds of damage or losing a diamond.

This comes down to preference, budget, and how you’d like to allocate that budget. Rings and settings can be very affordable if you keep things simple but you can easily spend more money on the rest of the ring than on the centerpiece.

Note that “designer” ring and setting designs come at a premium – one that you may not find worth the price. Be aware that most of the price premium you’re paying for is just a brand, not additional quality. If you’re trying to maximize the beauty of your ring for your budget, then spending money on a label you can’t see may not be high-value for you.

I strongly urge you to go try on a bunch of rings with your fiancée so you know what you both like and dislike.


Buy a 14K gold ring. 14K gold is more durable and less expensive than 18K gold and looks nearly identical – especially for white gold. Platinum looks the same and costs more so there’s no added value. Karat (not to be confused with Carat) is a measure of the purity or “fineness” of gold. It’s an antiquated system of denoting how pure gold is. Each karat represents 1/24th of the total amount so 14K gold is 14 parts pure gold and 10 parts other metals that make the jewelry more durable – mostly silver, copper, nickel, and zinc.

For those who might be interested in tungsten or platinum wedding bands, there’s a popular rumor that these bands cannot be cut off if your finger becomes injured and begins to swell. This rumor is part truth and part myth. Tungsten carbide is very difficult to cut, but it can technically be cut. More likely it will be cracked by applying increasing pressure from a highly leveraged clamp like a vise grip.

Titanium, while difficult to cut, can be cut with large bolt cutters. But even though these materials can be cut or broken off your finger, I would personally dissuade anyone from wearing one – especially if they have an active lifestyle. There’s always the risk that you can’t get to a vise grip, saw, or cutters quickly enough. Also, these materials are much more difficult to resize if necessary.

Bottom Line: Buy a 14K gold ring. After that, find out what style you want by going to a store and trying on a bunch of rings. If you don’t know what style your fiancée wants, a solitaire set with 4 prongs is a classic way to let the diamond simply speak for itself. Solitaire rings with prongs are also the least expensive style so you can swap them out and resize them at little or no cost once you’ve given your fiancée the ring.

Trying on Rings

I want to pause for a moment to make one final case for you to take your love and go try on a bunch of rings at your local jeweler. There so many decisions to make about both the ring and the diamond that you need help from the person who’s actually going to be wearing it. And understanding your future fiancée’s preferences will let you focus on the decisions that are less subjective, reducing your “Diamond Decision Fatigue.”

So pretty please, with sugar on top, take your future fiancée to a high-end jeweler and try on rings. I know that you’re thinking that it’s going to ruin the surprise. First, the fact that you want to get married is probably not really a surprise. Second, if you care about surprises, then you’re still going to surprise her with the ring and the moment.

I surprised my fiancée by asking her to marry me while we were at Burning Man. Then we went to a high-end jewelry store to learn more. We had a blast, were treated very well, asked a lot of questions, learned a lot education, and were even given free champagne after they found out that we were already engaged.

We got to see and try on a ton of different ring styles and materials and we got to talk about them openly. We got to hold a bunch of different diamonds, look at them under different lighting conditions, and with different magnifications.

We even got to size my fiancée’s finger with the right tools. Had we not done this, I would have had to guess by using another ring of hers. The size would have been wrong because, like most people, her left ring finger and her right ring finger aren’t the same size. If you get the wrong size, then your fiancée has to be without her ring for a few days – the last thing she wants right after you get engaged. Or worse yet, she could lose the ring because it’s too loose.

Finally, one last point: You don’t know what your future fiancée wants. Her mom doesn’t know. Her sisters don’t know. Because unless she’s gone through this process before, she doesn’t know what she wants yet. When we walked into the store, my fiancée wanted a cushion cut. When we were looking at rings in the show room she fell in love with the marquis cut (because that’s what princesses wear, duh). Then, as we learned more about each shape, we both knew – once and for all – that she wanted a brilliant round cut.


When people talk about cut, they’re usually mixing two separate concepts: cut quality and diamond shape. But the “4Cs and 1S” don’t make for a very good marketing campaign. Cut quality is all about how well the diamond is cut. We’ll discuss shape below.

Diamond cutting is a mix of art and science, both in terms of the decisions of how to cut a rough diamond but also in the actual execution of the cutting, which is aided more and more by computers, robotics, and laser cutters.

Rough diamonds are carefully analyzed to maximize value and minimize waste. This means that a diamond cutter might decide to cut a diamond in an optically less-ideal way in order to preserve more of the mass of the diamond. Even though the finished diamond will be less pretty, it will be larger, which they know will be appealing to consumers who are overly concerned with carat and size and don’t understand the importance of cut quality.

Cut and polish make diamonds pretty. Since one of the core reasons we’re buying a diamond is because they’re pretty, you should buy a very well cut diamond. And, unfortunately, poorly cut diamonds are still expensive. So given a fixed budget, it’s absolutely worth getting a slightly smaller diamond to show off all that fire and flare.

Cut is graded on a scale. The top tier is called “excellent” in the GIA certification system. But other systems use other words like “ideal” for their top tier cut.

The full GIA scale is: Excellent, Very Good, Good, Fair, Poor.

“A beautiful diamond looks the way it does because of three optical effects: white light reflections called brightness, flashes of color called fire, and areas of light and dark called scintillation. Pattern is the relative size, arrangement, and contrast of bright and dark areas that result from a diamond’s internal and external reflections. There must be enough contrast between the bright and dark areas to give the pattern a crisp, sharp look.” – GIA

Branded Cuts

Other diamond cutters and retailers, most notably Hearts on Fire, sell high-end cuts at a premium. These cuts are usually branded and trademarked. Hearts on Fire owns the trademark for “The World’s Most Perfectly Cut Diamond” meaning that no other diamond manufacturer can make that claim.

The vast majority of branded cuts are actually worse than GIA certified excellent cut diamonds because they have unnecessary cuts that stray from the proven standard brilliant cuts. A good rule of thumb is to avoid diamonds with fancy names, or names at all.

Hearts on Fire diamonds are a little bit different though. While they’re absolutely gorgeous – better than most GIA excellent cut diamonds – they are not a good value. So while cut is very important, once you have an excellent cut diamond, you’ve crossed the threshold and don’t need an even better cut. Hearts on Fire diamonds sell for a huge premium – over $6,500 more for zero tangible value in this side-by-side comparison of 1 ct diamonds.

It’s a great read – especially if you’re considering a Hearts on Fire diamond. One final note about Hearts on Fire. HOF doesn’t let a third party certify their diamonds. So even though their diamonds are beautiful, no third party is auditing their internal certification process.

Speaking of HOF, they made this great video that shows the entire process of selecting, cutting, and polishing diamonds. It’s worth a watch to understand the cutting process from start to finish. Any well cut diamond will go through a similar process, not just HOF diamonds:

Bottom Line: Get an “excellent” cut GIA certified diamond to maximize value. Skip branded diamonds unless you want to pay a premium for features and brand that no one can see.


Shape is exactly what it sound like: the shape of the stone. Again, it’s critical that you actually go put real rings on your fiancée’s real finger to fully understand the pros and cons of the different shapes.

Before my fiancée tried on a few rings, she wanted a cushion cut. Then she fell in love with the marquis cut. But once we learned more, we knew that the right cut for us was the brilliant round. Specifically, there’s a black “bow-tie” effect that occurs in nearly all marquis stones – even well cut stones. They’re also much more likely to catch on things which could potentially damage them or knock them loose.

While every shape we saw at the jeweler was pretty, as we learned more about diamonds it became obvious that the round brilliant shape showed off the a diamond’s natural qualities best. The 58 facets of a round brilliant cut diamond maximize light reflection. However, if you and your fiancée feel pulled towards a particular shape, get it!

Bottom Line: Go physically try on a bunch of different shape stones so you get a sense of what you and your fiancée really like. Put your favorites on side by side so you can compare them. Pick what calls to you. When in doubt, go with the round or princess (square) brilliant cut as they show off a diamond’s inherent qualities best.


Natural diamonds are formed under tremendous pressure and heat about 100 miles below the surface of the earth. During this process, impurities and misalignment of atoms can disrupt the crystal lattice in various ways. These imperfections are called inclusions and every diamond has them – even if they’re not visible to the naked eye.

When trying to maximizing value, we want diamonds that don’t have inclusions that are visible to the naked eye – a threshold that’s called “eye-clean.”

We definitely want an eye-clean diamond. But we don’t want to pay the extra money for a diamond that doesn’t have inclusions under 10x or 20x magnification. Money we save buying a diamond that’s eye-clean, but not substantially more perfect, can be saved or put towards a larger diamond.

The GIA clarity scale is a bit convoluted and each grade is usually referred to by its acronym. Each diamond is viewed by a professional grader under 10x magnification and then bucketed into one of these grades based on the type, size, location, and number of inclusions. Here are the grades from best to worst:

    • FL – Flawless
    • IF – Internally Flawless
    • VVS1 – Very Very Slightly Included 1
    • VVS2 – Very Very Slightly Included 2
    • VS1 – Very Slightly Included 1
    • VS2 – Very Slightly Included 2
    • SI1 – Slightly Included 1
    • SI2 – Slightly Included 2
    • I1 – Included 1
    • I2 – Included 2
    • I3 – Included 3

Clarity is what makes diamonds so hard to compare – cut, color, and carat are much more straightforward. Inclusions look different, come in all shapes and sizes, and can be located in important or unimportant places depending on how the diamond will be set. While this makes grading and selecting diamonds more difficult, it provides smart buyers with an opportunity to get a diamond with the lowest clarity rating that’s still eye-clean.

Buying something above VS1 is a waste of money and it’s possible to find a great I1 diamond. I recommend looking for diamonds that are in the middle, VS2 to SI2. And no matter what diamond you pick, make sure you know where the inclusions are and that they’re not directly under a large facet where they’ll be most visible.

Bottom Line: Don’t buy a diamond with a clarity rating higher than you can appreciate. Maximize value by purchasing an eye-clean diamond. Forget about anything with a higher clarity grade than VS1 and the right I1 could be a winner for you. Once you narrow down the scope of the other variables, clarity is one of the big areas where you’ll spend extra effort finding the right diamond.


Color is straightforward. There are two main variables to be aware of when it comes to color: the color grade and fluorescence. Both of these properties are listed on GIA certificates. Color grade is a alphabetical scale starting at D (colorless) and ending at Z. Obviously starting at D is confusing, which is why it’s the perfect system for diamonds (actually GIA claims that they start at D to differentiate themselves from other grading systems that use “AA” and “A” to grade color).

Colorless diamonds are much more rare than diamonds with a color. So naturally they’re more expensive. But unless you’re comparing a bunch of diamonds side by side in ideal lighting conditions, it’s basically impossible to tell the difference between similar grades.

This means that you can waste a ton of money buying a diamond that’s higher on the scale than we can see. Depending on the setting material and diamond shape, diamonds in the I to M range are good enough to appear colorless when worn.

Fluorescence occurs when light absorbs into a substance and is then re-emitted, usually as a different wavelength of light. For example, UV light (which the human eye can’t see but is in natural sunlight) can be absorbed into diamonds and re-emitted, giving the appearance that the diamond has a color – often blue. A faint fluorescence can actually make a slightly yellow diamond look less yellow in natural light, but it’s not wise to heavily rely on this effect since you can’t always control how much light in the UV spectrum is hitting your diamond. A faint or mild fluorescence is okay, but avoid diamonds with more since they can look cloudy, tinted, or oily in natural light.

Bottom Line: Color is a dimension you should be willing to sacrifice on, to a point. Color is easiest to see when you have multiple diamonds of different colors side by side – something that doesn’t happen often once a diamond is in a setting and being worn. In the case of multiple diamonds in a piece, it’s important that the colors be similar.


If you’re following my advice of setting a budget first, this is one of the simplest factors to consider.

You might think that you just want to buy the largest carat diamond that’s within your budget, but that’s not quite right.

First off, it’s important to know that carat is a measure of mass not size or volume. 1 Carat = 200 mg or one 5th of a gram. Once again, we don’t really care about what’s being certified, we care about the final look of the diamond. And you don’t see mass, you see size. So while the size of a diamond is highly correlated with it’s mass, there are other important factors to consider.

The second reason we care more about the size of the diamond rather than the mass is that you can – depending on the cut quality – have a diamond that’s large in mass but small in the visible area.

Do not fall for the common temptation to sacrifice cut for carats. Cut quality and geometry are what make diamonds beautiful. Getting a slightly larger diamond will not make up for ugliness.

Finally, there is such a thing as too big. While I don’t think this will be a common scenario unless your fiancée has extremely small hands or your budget is very large, it is possible to buy a diamond ring that’s too large. Very large stones sit further away from the wearer’s finger meaning that they’re more likely to hit things or catch on fabrics. And really large ring can look cartoonish and fake.

Bottom Line: Get everything else right – especially cut and clarity – and then get the largest carat diamond that’s in your budget.

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