Diamond Buying Guide

A good understanding of diamonds is essential if you want to get the best quality and price.

gia certificate

GIA Certificate

To select the best diamond, you will need to start with the diamond’s certificate (also known as a grading report). The certificate will give you detailed information about the “4 C’s” that you’ll need in order to make the correct buying decision. All quality center diamonds will come with a certificate. The two most respected are GIA (Gemological Institute of America), and AGS (American Gemological Society). They both are well recognized for their accurate grading standards. At the high end, AGS is often preferred because of their more comprehensive cut and light performance specifications.

Where to Start When Buying Your Diamond

Choosing a diamond centers on selecting the shape, size, color, clarity, cut and quality. Let’s start with the shape…

Diamond Shape

Diamonds are offered in several different shapes. The three most popular shapes that we will cover in this guide, are the Round cut, Princess Cut and Cushion cut. Selecting the diamond’s shape is all about personal style and preference.

diamond shapes

There are those that say that “personality traits” may help predict which diamond shape your bride-to-be will prefer…

  • Round: traditional romantic
  • Princess: trendsetter and outgoing
  • Cushion: style and romance

The round is the most popular, followed by the Princess, with the cushion recently coming into fashion.

You can visit our Diamond Shape Guide and Does Your Diamond Reflect Your Personality pages for more ideas.

The Four C’s

Once you’ve chosen the shape of the diamond, it comes down to selecting the diamond’s size and quality, which brings us to the “Four C’s” – cut, color, clarity, and carat weight.

Carats

Everyone knows about carats. It’s how big the diamond is, and the bigger the better! However, technically speaking, a carat is a measurement of the diamond’s weight, not its size. (One carat is 200mg). Depending on how a diamond is cut, two diamonds of the same carat weight can appear visually slightly larger or smaller from one another. But in general, the more carats, the bigger the diamond appears.

Large diamonds are expensive. Due to the scarcity of larger diamonds, the price of a diamond grows exponentially as its size increases. According to a recent survey by The Knot, the average size of an engagement ring’s center diamond is 1.1 carats. What size you can afford will depend on your budget and the quality (cut, color, clarity) of the diamond…

Cut

Cut can be confusing, because the diamond industry uses it in two different ways. One, is in describing the diamond’s shape, such as Round cut, Princess cut, etc.

diamond cut

The other use, which is the one listed in a GIA or AGS grading report, is in describing how well proportioned the diamond is. The better a diamond is proportioned, the better its light performance: sparkle, brilliance, scintillation and fire.

In general, try to stick to diamonds graded Excellent or at least Very Good. At the high end are diamonds considered “Super Ideal” or “Hearts and Arrows” quality.

Like carats, the better a diamond is proportioned, the more expensive it will be. But unlike carats, the price doesn’t grow exponentially. An Excellent cut diamond is only about 15% more expensive than a Very Good cut. So unless you’re on a tight budget, select an excellent cut; you’ll get a bit more added sparkle if you do.

Color

The term color is a measurement of the degree of yellowish tint that is visible in a “white” diamond. Graded on an industry-standard scale from D (colorless) to Z (light yellow), the less yellowish tint visible in the diamond the more expensive it will be.

diamond color

Most people find the best value in the G,H,I and maybe J (near colorless) range. These diamonds can be thousands of dollars less expensive than the D,E,F (colorless) diamonds, yet color-wise, almost indistinguishable from their more expensive counterparts.

Clarity

A diamond’s clarity is a measurement of how many imperfections it has. Diamonds are graded on a scale from F (flawless), IF (internally flawless), VVS1-VVS2 (very very slightly included), VS1-VS2 (very slightly included), SI1-SI2 (slightly included) through I1-I2-I3 (included).

diamond clarity

In general, imperfections in diamonds rated F/IF through VS1-VS2 will not be visible to the unaided eye.

The best value will be in diamonds rated VS1 or VS2.

You can find great value in SI1/SI2 diamonds, but you need to examine them visually to make sure they are “eye clean”. For example, James Allen’s “360° Diamond Display Technology” lets you view a magnified video of each diamond in their inventory. So with a little extra work, you can save yourself quite a bit of money.

For more information on the Four C’s, take a look at our Diamond Pricing and the Four C’s guide.

In addition to the 4 C’s, there are a few other factors to consider when selecting your diamond, specifically: Polish, Symmetry and Fluorescence. Visit our Diamond Anatomy and Pricing page for more details.

For Diamond Connoisseurs

ASET image

ASET image of a Super Ideal Cut Round Diamond

As mentioned earlier, how well a diamond is cut will determine its light performance. At the high-end, diamond connoisseurs seek out the “Super Ideal” or “Hearts and Arrows” cut diamonds.

These diamonds are cut for maximum light performance, and during the cutting process, the cutter will sacrifice carat size for optimizing the diamond’s proportions for the best sparkle and brilliance.

So for a given carat size these diamonds can be several thousand dollars more expensive.

Reflector technology tools such as the ASET (Angular Spectrum Evaluation Theory), introduced by the American Gem Society in 2005, can help the diamond connoisseur to objectively evaluate the cut proportions of these high-end diamonds,

Diamond Guidelines Pricing Table  

According to The Knot’s third annual Engagement & Jewelry Study, the average price of an engagement ring is $5,403. In addition, the average size of the center diamond is 1.1 carats (source). Figuring a typical breakdown of 75% spent on the center diamond and 25% spent on the setting, then on average a 1.1 carat diamond will be $4052, with a setting of $1351.

Which interestingly enough is almost exactly what our diamond guidelines pricing table (below) says should be the price for a 1.1 carat diamond when optimized for best price.

Our diamond guidelines pricing table is our best recommendations and advice for selecting Round cut, Princess cut, and Cushion cut diamonds. There are three categories for each carat range: Best Price, Balanced and Connoisseur.

“Best Price” are diamonds optimized for carat size, with a J (nearly colorless) color, SI2 clarity (which should be visually inspected to be “eye clean”), and a Very Good/Excellent cut. While these diamonds may not sparkle quite as much as a “connoisseur” diamond, they will still have a pretty nice sparkle, with the added bonus of being around half the price!

“Balanced” are diamonds selected for a balance between best price and best light performance. With a color ranging between I,H,G (nearly colorless), VS2 clarity, and Excellent cut.

“Connoisseur” are diamonds optimized for maximum light performance (brilliance and sparkle). With a color ranging between I,H,G (nearly colorless), VS2 clarity, and “Super Ideal” cut. Typically, they will be AGS certified diamonds and will have ASET images for light performance evaluation. These will be the highest quality (and most expensive) diamonds for each category (Often twice as expensive as a diamond optimized for best price).

Diamond Guidelines Pricing Table

Carats Best Price Balanced Connoisseur
  best price diamond balanced diamond connoisseur diamond
0.5 Round J/SI2/VG, $1200
Princess J/SI2/VG, $790
Cushion J/SI2, $890
Round I/VS2/EX, $1600
Princess I/VS2/EX, $1020
Cushion I/VS2, $1000
0.6 Round J/SI2/VG, $1500
Princess J/SI2/VG, $1000
Cushion J/SI2, $1100
Round I/VS2/EX, $2000
Princess I/VS2/EX, $1200
Cushion I/VS2, $1200
0.7 Round J/SI2/VG, $1650
Princess J/SI2/VG, $1500
Cushion J/SI2, $1600
Round I/VS2/EX, $2400
Princess I/VS2/EX, $1900
Cushion I/VS2, $1800
0.75 Round J/SI2/VG, $1900
Princess J/SI2/VG, $1600
Cushion J/SI2, $1700
Round I/VS2/EX, $2800
Princess H/VS2/EX, $2700
Cushion H/VS2, $2600
0.8 Round J/SI2/VG, $2400
Princess J/SI2/VG, $2000
Cushion J/SI2, $1800
Round I/VS2/EX, $3000
Princess H/VS2/EX, $2300
Cushion H/VS2, $2100
0.9 Round J/SI2/VG, $3000
Princess J/SI2/VG, $2500
Cushion J/SI2, $2200
Round I/VS2/EX, $4500
Princess H/VS2/EX, $3700
Cushion H/VS2, $3000
Round I/VS2/ID, $6400
Princess G/VS2/ID, $4600
1.0 Round J/SI2/VG, $3500
Princess J/SI2/VG, $2800
Cushion J/SI2, $2700
Round I/VS2/EX, $6000
Princess H/VS2/EX, $4400
Cushion H/VS2, $3900
Round I/VS2/ID, $7800
Princess G/VS2/ID, $6200
Cushion G/VS2, $8600
1.1 Round J/SI2/VG, $4000
Princess J/SI2/VG, $3700
Cushion J/SI2, $3000
Round I/VS2/EX, $6900
Princess H/VS2/EX, $5200
Cushion H/VS2, $5000
Round I/VS2/ID, $8700
Princess G/VS2/ID, $6600
Cushion G/VS2, $9700
1.2 Round I/VS2/EX, $7200
Princess H/VS2/EX, $6000
Cushion H/VS2, $5500
Round I/VS2/ID, $10000
Princess G/VS2/ID, $7300
Cushion G/VS2, $11000
1.5 Round I/VS2/EX, $11000
Princess H/VS2/EX, $10000
Cushion H/VS2, $9500
Round I/VS2/ID, $15000
Princess G/VS2/ID, $12000
Cushion G/VS2, $18000

While you can get a slightly cheaper diamond by going below our guidelines, it’s not recommended. We don’t recommend a cut below “Very Good” as you lose just too much sparkle. You should also avoid I1-I3 diamonds as they have too many inclusions, which can jeopardize the integrity of the stone as well as its brilliance. However, you can try a K (faint yellow) colored diamond, especially if your ring setting uses yellow gold, which will help mask the yellowish tint of the K colored diamond.