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The Concise Guide to Buying a Diamond

by Adriana Perez-Nakamura
Last updated on August 20, 2023

A lot of people think that buying a diamond begins by picking a ring you think your partner will like and checking out. We’ve seen it happen in typical mall chain jewelry retailers. Customers get no real information, like a guide to buying a diamond. They just buy a diamond ring that looks good to them.

With the explosion of online retailers, more customers have access to information about purchasing diamonds. They are quickly discovering all the benefits of buying a diamond online rather than in a physical jewelry store.

What Are the 4Cs of Diamond Quality?

Claudette Ring. Guide to buying a diamond.

The 4Cs is a grading system created by the Gemological Institute of America. This grading system is standardized across the jewelry industry. According to the 4Cs, there are four main pillars of diamond quality and value:

  • Cut Grade/Cut Quality
  • Clarity Grade
  • Color Grade
  • Carat Weight

Each factor has its own charts and standards to determine quality. While the 4Cs are vital factors to think about when you buy diamonds, we should note that there’s still more to diamonds beyond the 4Cs–but more on that later.

Diamond Cut Quality

Lumiere Bridal Set

Your diamond’s cut quality has a direct effect on its light performance. Its sparkle, fire, and overall look depend on how well-cut the stone is. A mediocre cut quality impacts the return of light in a diamond; it can also compromise durability

Diamond Cut Grades

The GIA created a cut grade chart for diamonds, but only for round diamonds. A round diamond is the only diamond shape that can achieve perfect diamond proportions and symmetry.

Round diamonds are the only diamond shapes with official cut grades on diamond grading reports distributed by the GIA (and most other laboratories). However, the American Gem Society (AGS) also offers ideal cut grades on their reports for princess cut diamonds and cushion diamonds.

You should know that just because you choose a round diamond with an Excellent cut grade doesn’t mean it’s the best. Cut grade is a major factor in overall cut quality of a round diamond, but other important details could make one Excellent cut graded diamond a better diamond than another.

Do Fancy Shape Diamonds Have Cut Grades?

The majority of diamond certificates don’t show cut grades for fancy shape diamonds. Fancy shape diamonds are shapes besides round. These shapes aren’t perfectly balanced like round diamonds are, so there’s no perfect standard.

This can be confusing if you do your diamond shopping online. Many jewelers separate their fancy shape diamonds online by dividing them into cut grades. However, this is to narrow down the general quality of the diamond. The grading report won’t have a cut grade (unless it is from AGS).

Instead, fancy shapes have their own guidelines to ensure “ideal/excellent cut quality.” While round diamond cut quality is more standardized, the suggested proportions and cut quality details are in a range for other shapes.

Additional Elements of Cut Quality

So, what guidelines should you follow if you want something besides a traditional round diamond engagement ring?

Length to Width Ratio

The first thing to do is make sure the outline of your shape has an attractive length to width ratio. The L/W ratio of a diamond controls how narrow or elongated the shape is. It is the ratio of a diamond’s length to its width.

For some shapes, a longer or shorter length to width ratio is a preference. But with shapes like a heart cut diamond, ratios outside their suggested range can make the shape look distorted or disproportionate.

Polish and Symmetry

Arielle ring.

The polish of a diamond is its surface finish. Diamonds often have blemishes, which are clarity imperfections on the surface of the diamond. Most often, these affect the crown and table facets (the top).

A diamond’s symmetry is how the facets are proportioned and arranged on the surface. Symmetry is important because it affects the way light reflects off your diamond’s facets. Disproportionate facets can result in less brilliance and more light leakage.

Both polish and symmetry are listed as specific details of your diamond. A diamond’s polish and symmetry can be graded as Excellent, Very Good, Good, Fair, and Poor, just like diamond cut grades.

Table and Depth Percentage

The table percentage is the size of the flat top facet of the diamond in relation to its diameter. The table facet is the biggest facet of your diamond.

If the table facet percentage is too large, it can affect the diamond’s appearance and sacrifice brilliance. Light won’t bounce out as well if your table is too big.

The depth percentage is the height of the diamond in relation to its diameter. If you go outside the suggested depth percentage range for a diamond’s shape, it will affect appearance and brilliance, too.


Your diamond’s fluorescence is how the diamond reacts to UV light. Under UV lighting, fluorescent diamonds exhibit a blue glow. Diamond fluorescence ratings are Very Strong, Strong, Medium, Faint, and None.

  • None: Does not emit any visible fluorescence under UV light.
  • Faint: Emits a slight fluorescence that may be visible under UV light, but not necessarily to the naked eye.
  • Medium: Emits a moderate fluorescence that is often visible to the naked eye, particularly under natural daylight or in fluorescent lighting.
  • Strong: Easily visible to the naked eye, even in normal lighting conditions.
  • Very Strong: May appear hazy or cloudy and can sometimes affect the appearance of the diamond. Glows blue under bright sunlight.

Fluorescence only affects your diamond visually and tends to be a personal preference. Diamonds with no fluorescence are considered better quality and are more valuable, but it doesn’t greatly impact the diamond.

In bright sunlight, diamonds with Medium, Strong, and Very Strong fluorescence give off a blue glow due to the UV rays from the sun. Some people prefer the blue tint, especially if it offsets the yellow tint of a lower color grade.

Diamond Clarity

Diamond clarity is the assessment of a diamond’s natural inclusions and surface blemishes. A clarity grade is awarded to diamonds on their grading reports. The GIA gives clarity grades to diamonds according to the size, location, number, type, and relief (how noticeable it is in comparison to the diamond’s background).

Diamonds with low clarity grades can have visible imperfections to the naked eye. If your diamond’s clarity grade is a VS2 or higher, it’s considered to be an eye clean diamond. Eye clean diamonds have no visible inclusions to the naked eye, but may have very slight inclusions under magnification. Higher clarity grades have inclusions viewable under further magnification.

For more information on diamond clarity, see this chart.

Diamond Color

The presence of a yellow tint determines diamond color grades. Diamonds in the DEF range of color grades are more valuable and expensive. However, the average person chooses color grades in the Near Colorless range (GHIJ) for their engagement ring.

Though value dictates the “best color grade,” it is an optical selection. Some people are more visually sensitive to yellow tints than others. Others make a conscious choice to buy warmer color diamonds that complement their skin tone.

Diamond Carat Weight

Most consumers are familiar with the concept of carat weight, but they often some have misinformation. For example, we constantly hear carat weight described as the size of your diamond. However, larger carat weight doesn’t always increase a diamond’s face-up size.

For example, round diamonds need to be cut much deeper than other shapes in order to achieve excellent brilliance. An emerald cut diamond is cut much more shallow, so more of its weight is distributed at the top. That’s why a round one carat diamond appears smaller than a one carat emerald cut diamond. They’re the same weight, but not the same size.

For many of the diamond grades, there’s not a huge jump between grades right above and below one another. Typically, if you compare a low clarity grade to a high clarity grade, you’ll see a couple thousand dollar difference.

But when you jump from a 1 carat diamond to a 2 carat, you might be shocked to see how much the diamond prices increase. As a diamond’s carat weight increases, its clarity grade, color grade, and cut quality must match. Choosing low grades in the other three Cs will result in a larger but duller diamond engagement ring.

And despite its lack of brilliance, the diamond’s price will still be high because of its size. People assume that a 2 carat diamond should cost the same as two one carat diamonds. But it is harder for diamond cutters to facet diamonds of larger carat weights and minimize the clarity and color grades of the rough diamond.

It’s our advice that you don’t go for the biggest diamond over other important factors of buying a diamond. You can have a big diamond, but will it be beautiful? Probably not. How large a diamond is doesn’t reflect its overall quality.

Diamond Shape

Waverly ring. Guide to buying a diamond.

Your diamond shape is a preference, but you should be aware that each shape has its pros and cons. Every diamond shape can create a gorgeous diamond engagement ring so long as its grades and quality factors are good.

Some diamond shapes will cost more than others of the same quality and same carat weight. Typically, a brilliant cut diamond ring will cost more than a step-cut diamond. Step-cut diamonds have longer facets and more viewable areas for clarity imperfections if the color grade is low.

Your brilliant cut diamonds are:

  • Round diamonds
  • Princess cut diamonds
  • Oval diamonds
  • Cushion cut diamonds
  • Radiant cut diamonds
  • Marquise cut diamonds
  • Heart cut diamonds
  • Pear cut diamonds

Your standard step cut center stone shapes are:

  • Emerald cut diamonds
  • Asscher diamonds

A round diamond tends to be more expensive than other diamonds of the same carat weight, usually due to both demand and its ability to have perfect proportions.

From ideal cut diamonds came specialty cuts like the super ideal cut diamond and beyond. These diamonds come with an additional premium cost.

That being said, there’s no diamond shape whose brilliance is as spectacular as a round diamond engagement ring.

Diamond Certificate

Diamond certification is essential when picking out your diamond engagment ring. Many engagement rings in jewelry stores are uncertified, whereas most diamonds online come with their own diamond certificates.

A diamond certificate or grading report is sort of like a birth certificate. A grading report states that a reputable grading laboratory has made sure your diamond meets the specifications the retailer is advertising.

Diamond certificates have all the details of your diamond’s 4Cs and more. Most reports have a clarity plot to show you where inclusions are located on your diamond. This can also help identify your diamond ring if you believe a jeweler switched out your diamond for another.

You should know that not every grading report is from a reputable jeweler. Some jewelry stores create their own grading standards. We recommend purchasing diamonds with grading reports from independent gemological laboratories, as these are impartial to any specific brand or store.

Our lab grown diamond rings may come with grading reports provided by the GIA, IGI, and GCAL laboratories. All of these labs are reputable.

How to Pick a Ring Setting for Your Diamond Engagement Ring

Each ring setting has its own attractive qualities as well as its own drawbacks. No one setting is necessarily better than another. But when choosing a ring setting for an engagement ring, you should consider your lifestyle.

If you know you have an active lifestyle or active job, you may not want engagement rings with high profiles. A propped up cathedral or high profile solitaire ring might not be ideal for your everyday life.

Your ring metal is another detail of the ring setting to consider. Most retailers offer engagement rings in white gold, yellow gold, rose gold, and platinum. In-store retailers often have more white gold jewelry in stock than anything else.

While the color of your gold ring setting doesn’t change its price, the amount of gold does. Expect 18K gold engagement rings to cost more than the same diamond rings crafted in 14k gold. Platinum engagement ring settings often cost more than both of these.

How Much a Good Quality Diamond Costs

Diamond prices aren’t as cut and dry as many buyers assume. Some first-time diamond shoppers might think a big diamond is a good quality diamond. As you’ve probably learned by now, a good quality diamond requires a balance of many factors, not just one.

We advise you not to put all your eggs in one basket or choose the highest grades in every category; if you do, you’ll pay a significant cost. Many factors can be a preference and a choice if monetary value is not as important to you as your budget. That’s why it’s important to compare diamond prices and quality when choosing a loose diamond for your engagement ring.

You can save money by purchasing one of our stunning lab grown diamond engagement rings, which come at a 20-40% lower cost. Lab created diamonds are real diamonds in every way; there just formed under laboratory conditions rather than in the Earth.

The Most Important Factor When Buying a Diamond Ring

Though it’s important to have a balance of diamond grades, styles, and other quality factors, there is one diamond detail that stands above the rest. This is cut quality.

It’s true that many people won’t notice the difference between a diamond with Excellent cut quality vs one with Very Good quality. But many can distinguish a Good quality diamond from an Excellent one.

The sparkle and brilliance of a diamond is usually why people want to buy it. The combination of white and rainbow color light is a stunning sight to behold. But if the cut quality of your stone is sub-par, the beauty is lessened.

Diamonds that leak light are still very expensive, especially if they are larger carat weights and have higher grades in other areas. But there are standards on cut quality that need to remain in order to have a beautiful diamond. A poor cut can not only affect a diamond’s sparkle, but also its durability.

It’s my advice that you never sacrifice diamond cut quality for another factor like color grade, clarity, or carat weight. Both clarity and carat weight are relative to your own eye.

Final Advice on the Diamond Buying Process

I hope you found this diamond buying guide to your liking. There are many, many different things to consider before making a diamond purchase.

You now know that a diamond’s quality isn’t affected by a single factor. It’s not necessary to have the biggest diamond or a flawless diamond in order to have an elegant engagement ring.

Instead, you know that diamond pricing comes not only from demand and popularity, but also from all of its grades and additional details. Even your diamond shape can affect the price per carat of your loose diamond.

Buying a diamond that is lab grown can be a great option for anyone wanting to save money and make a more ethical purchase than a conventionally mined diamond ring.

Most of choosing a diamond for your engagement ring is up to your personal taste and style. However, cut quality is something you should never sacrifice. Other major factors like clarity, color, and carat weight should be chosen according to your tastes and budget.

And if you’re still not sure how to buy a diamond online, feel free to consult one of our diamond experts as your own personal diamond buying guide!