Ultimate Diamond Buying Guide 2025

How To Choose The Right Diamond Shape?

Why Diamond Shape Matters

The shape of a diamond serves as the foundation for its overall aesthetic and is pivotal to the design of the final jewelry piece. While the round brilliant remains the most popular and versatile shape, a wide array of alternatives offers unique appeal and distinctive styling options.

Key Considerations for Diamond Shape Selection

Grading Standards: It’s important to note that shapes other than round are not typically graded for cut, a critical component influencing a diamond’s brilliance and fire. This lack of standardized cut grading for fancy shapes necessitates a nuanced understanding when assessing their quality.

Length-to-Width Ratios: The length-to-width ratio provides a numerical representation of a diamond’s proportions, which significantly impacts its appearance. For example, a diamond with a length of 6.00 mm and a width of 4.00 mm has a ratio of 1.5:1, creating a balanced rectangular profile.

Diamond Shapes Chart

What Is Diamond Length To Width Ratio?

This ratio numerically illustrates how long and wide the stone appears from the face-up view. Expressed as “L:W”, it’s determined by dividing the length of the diamond by its width. For example, if a diamond had a length of 6.00 mm and a width of 4.00 mm, the length-to-width ratio would be 1:5.

Which Length To Width Ratio Is Best For Each Shape?

Suggested Length-to-Width Ratio Chart

• Round Brilliant: 1.0 – 1.03
• Princess: 1.0 – 1.05
• Cushion (square): 1.0 – 1.09
• Cushion (rectangular): 1.15 – 1.25
• Emerald: 1.50 – 1.75
• Asscher: 1.0 – 1.05
• Oval: 1.30 – 1.50
• Pear: 1.45 – 1.75
• Marquise: 1.85 – 2.1
• Radiant (square): 1.0 – 1.05
• Radiant (rectangular):  1.15 – 2.0
• Heart: 1.0 – 1.1
• Trillion: 1.0 – 1.1
• Baguette: Around 5.1

Shape-Specific Characteristics

• Visual Size (Face-Up Value): Certain shapes, such as pear, oval, marquise, emerald, and trillion, appear larger per carat due to their expansive table facets. This characteristic is ideal for maximizing visual presence.
• Affordability: Shapes like radiant, cushion, princess, asscher, and emerald tend to yield more from the rough, often making them more cost-effective options compared to round brilliants.
• Brilliance and Sparkle: Round brilliants remain the benchmark for light performance, though radiant and cushion cuts also deliver exceptional brilliance.
• Durability Concerns: Shapes with pointed edges, such as pear, marquise, princess, and heart, require protective settings to minimize the risk of chipping.
• Value Retention: Round brilliant diamonds hold their value best due to their enduring popularity and superior light performance. Collection-quality round brilliants often command premium pricing at auctions and among collectors.

Choosing the Right Carat Weight

*PriceScope Priceless Tip: You can’t judge a diamond’s size by its carat weight, you need more information.

Understanding Carat: Carat weight, equivalent to 200 milligrams, is a primary factor influencing a diamond’s value. However, a diamond’s visual size is also dictated by its cut quality and dimensions.

Key Concepts in Carat Weight

• Physical vs. Visual Size: Bright lighting in retail environments can exaggerate a diamond’s size perception. Superior cut quality ensures proper light reflection, maintaining apparent size across various lighting conditions.
• Total Carat Weight (CTW): The aggregate weight of all diamonds in a piece of jewelry, such as a halo ring, is often presented as a single figure. For example, a 0.75 ct center stone with 0.25 ct of accent stones totals 1.00 CTW.

Selecting Carat Weight with Confidence

Superior cut quality complements carat weight by maximizing visual spread and brilliance. For instance, a 0.80 ct diamond with excellent cut proportions may appear larger and more vibrant than a poorly cut 1.00 ct stone.

Proportionate Spread

Diamonds with optimal proportions balance depth and table size, ensuring no light is lost to leakage. A diamond’s grading report provides its external measurements in millimeters, allowing professionals to assess its physical spread and face-up size accurately.

What Is A Good Carat Weight?

The best carat weight is one that has proper physical and visual spread, looking as large as it should in all lighting environments. Choosing a 1.00 ct diamond over an 0.80 ct diamond makes no sense if the 0.80 ct diamond appears larger than the 1.00 ct diamond in normal lighting.

The Importance of Diamond Cut

*PriceScope Priceless Tip: Unlike color and clarity, where high grades are strict and rare, more than 60% of round brilliants receive the “Excellent” cut grade, so you need more information to make decisions.

Cut quality holds unparalleled significance in determining a diamond’s overall appearance and value. While high grades for color and clarity often show minimal variation, diamonds with the same “top” cut grade can differ significantly in brilliance and fire. This variability underscores the critical need to assess cut beyond surface-level grading labels, as over 60% of round brilliants receive an “Excellent” grade, yet only a fraction achieve optimal light performance.

Key Points on Diamond Cut Grading and Its Impact

• Variability Across Laboratories: Cut grading systems are not standardized across all gemological laboratories. The GIA, for instance, only introduced cut grading in 2006, leading to diverse grading methodologies. This inconsistency necessitates deeper scrutiny by gemologists to ensure quality.
• Impact on Other Diamond “Cs”: Superior cut quality enhances visual spread, brightness, dispersion, and scintillation, improving face-up color appearance and masking inclusions. Well-cut diamonds maintain brilliance and dynamic light performance in all environments.

Challenges in Balancing Cut and Weight

Weight Retention Over Beauty: Many diamonds are cut to prioritize carat weight rather than brilliance. Such steep-deep cuts maximize yield but compromise light return, creating darker, less lively stones.

Subset Classifications:

• Steep-Deep Diamonds: Common but suboptimal for light performance.
• PriceScope Ideal: Proportionate cuts that reflect light efficiently, ensuring brightness and fire.
• Super-Ideal: A rare category showcasing scientifically precise proportions and symmetry, often displaying Hearts & Arrows patterns.

What Are The Diamond Cut Subsets?

The PriceScope community refers to several subsets of round brilliant diamonds. Steep-deep diamonds are most abundant. Producers use wide (steep deep) cutting angles to increase the diamond’s final weight, maximizing yield. Unfortunately this reduces their size appearance and creates darkness when removed from bright lights. The PriceScope Ideal is cut with proportionate angles which successfully reflect and return light back to the viewer’s eyes as brightness, fire, contrast, and sparkle. The Super-Ideal is a rare subset, cut within a small range of scientifically proven “ideal” proportions and  further fine-tuned to display Hearts & Arrows in a specialized viewer.

What Is The Holloway Cut Advisor?

The Holloway Cut Advisor (HCA) is an analytic tool that uses measurements of a round brilliant diamond to calculate potential light return, fire, scintillation and spread. When you register with PriceScope you can analyze three diamonds for free. HCA scores are also included in PriceScope round diamond search results.

Use Our HCA To Hit The Cut Quality Bullseye

What is Ideal Scope?

The Ideal Scope is a portable diamond brilliance and leakage gauge. A lens with a hot pink reflector lets you see how much light comes from a diamond to your eyes. The most brilliant diamonds have pink/red (brightness) with a symmetrical black star (contrast) and minimal white or pale areas (leakage).

Best Practices for Evaluating Cut Quality

1. Proportional Analysis: Use tools like HCA or detailed grading reports to examine average proportions.
2. Performance Imaging: Request Ideal Scope or ASET images for a comprehensive understanding of light performance.
3. In-Person Assessment: Whenever possible, complement analytical tools with physical inspection under varied lighting conditions.

What Is Diamond Leakage?

Light entering a diamond will either reflect and shoot up to the viewer’s eyes (as brightness) or escape through the bottom (as leakage or windowing). In general terms, brightness is desirable, leakage is to be avoided.

How To Choose The Right Diamond Color?

*PriceScope Priceless Tip: The most purchased diamond colors are F-G-H or I, set in white gold or platinum.

Diamond Color influences price the most after carat weight. A diamond’s color was caused by chemicals in the earth where it formed. Most of the world’s diamonds are yellow or brown. The objective for most people is to get a diamond that appears colorless, also described as “white.”

How Is Diamond Color Graded?

Most diamonds are graded on a scale ranging from D, which has the least color, all the way to Z, which is light yellow or possibly light brown. Other colors, and stronger levels of yellow and brown, are classified as fancy colored diamonds, and are graded on a different scale.

Do I Need To Spend Big To Get A Colorless Stone?

Most people cannot detect a difference of 2-3 color grades unless the diamonds are placed next to each other, especially in the colorless (D-E-F) and near-colorless (G-H-I-J) ranges. With that said, taste comes into play. For those who love the icy appearance and rarity of a colorless diamond the extra spend may be worth it.

How Does Diamond Shape Affect Color?

Fancy shapes may reveal more color than round brilliant cuts in the face up position because they have broader facet arrangements. This is largely a non-factor in diamonds graded DEF. The potential for more visible color appearance or color concentration increases the more you consider diamonds graded GHIJ and below.

Is diamond color graded upside down?

Yes. Gemological laboratories perform D to Z color grading with the diamond upside down and viewed through the side because of three factors which may influence color appearance in the “face-up” position: The diamond’s shape, the way the diamond was cut and the possible presence of diamond fluorescence.

Do Larger Diamonds Show More Color?

Yes. As they get larger in size, diamonds show more color. As diamonds increase in carat weight the presence of color becomes more noticeable, simply because whatever color exists throughout the diamond occurs takes on more mass. The presence of color in diamonds graded K and below becomes especially noticeable at weights above 2.50 – 3.00 carats.

What Is Undisclosed Undertone?

Undisclosed undertone is something that isn’t disclosed on diamond grading reports. It’s a subtle or not-so-subtle brown, grey or green undertone which influences overall color appearance. This issue is disclosed among traders but isn’t always communicated by diamond sellers to consumers.

How Does Cut Affect Diamond Color?

Remember that diamonds are color-graded upside down, viewed through the side. “Face-up” color is the diamond’s color appearance when viewed from the top. In well-cut diamonds light gets in and out on shorter ray-paths with greater intensity. This can cause the appearance of less color when the diamond is seen from the top.

Alternately, if the diamond is cut so that light escapes through the bottom – or bounces around inside – the color within that diamond may be exaggerated when seen from the top.

Which Diamond Colors Are Recommended For Different Ring Settings?

Round brilliant diamonds benefit from kite-shaped facets which promote sparkle, so they can be set in white metal in colors from D-J. Colors below J are well-suited for yellow metal settings. Colors with brown undertone look great in rose-gold settings. Fancy shapes are recommended for setting on a different schedule. See all metal recommendations here.

Does Color Affect Diamond Price?

Diamond Color influences price the most after carat weight. Collection quality diamonds are those with color and clarity combinations which trade for the highest values and continue to hold that value best over time. Combining a non fluorescent, D color, E color, or F color with Flawless, Internally-Flawless, VVS1 or VVS2 clarity gives a diamond collection quality status in the eyes of diamond professionals and enthusiasts. Some people choose high color and clarity combinations for this reason.

How Do You Choose The Right Diamond Clarity?

*PriceScope Priceless Tip: The most purchased clarity grades are VS1, VS2 and “eye clean” SI1.

– Definition on diamond clarity.

What Is Diamond Clarity?

The world’s natural diamonds formed between 1-3 billion years ago, 100 miles beneath the earth’s surface. As they grew, chemicals and elements present in the earth became trapped within their crystal lattices. Diamond Clarity evaluates a gemstone’s relative freedom from such internal characteristics, classified as inclusions, and from surface characteristics, classified as blemishes.

How Is Diamond Clarity Graded?

A gemologist analyzes clarity by looking down through the top of the stone at 10-power (10X) magnification. All inclusions and blemishes seen at 10X are considered when deciding the clarity grade. There are 11 different clarity grades.

What Are Inclusions?

Inclusions are characteristics trapped within the diamond.

Twinning Wisps Inclusions shown below

Image Source: Whiteflash

What Is An Eye-Clean Diamond?

Many people just want an “eye-clean” diamond, meaning one which has no inclusions invisible to the naked eye. There is no laboratory definition for this, but a PriceScope survey of gemologists resulted in this consensus:

Eye-Clean: No inclusions visible to the unaided eye when viewed from the face up position in daylight equivalent or fluorescent lighting between 6-12 inches from the eye using 20/20 vision.*

See a diamond clarity chart showing eye-clean clarity grades.

Eye Clean VS 10x, What’s The Difference?

Eye-clean is determined when viewing a diamond with the naked human eye. 10X examination is performed viewing the diamond with a magnifying loupe or microscope.

How To Assess Diamond Clarity Confidently?

Successful online sellers like our recommended PriceScope vetted vendors, have methods of reliably classifying and communicating diamond clarity, whether you’re examining it in-person or purchasing online. They also offer liberal inspection periods and free returns so you can make your purchase with complete confidence. You can read about how to choose diamond clarity with confidence here.

What Factors Affect Diamond Clarity?

In addition to visibility at 10 power magnification, gemologists also consider Location, Number, Color, Size and the Nature of inclusions and blemishes when deciding the diamond clarity grade. You can read definitions for each of those additional factors on our Diamond Clarity page.

What Are Clouds Not Shown?

In clarity categories VS2, SI1, SI2 and below the comments “clouds not shown” or “additional clouds not shown” typically indicate the diamond grader considered them a non-issue. The comment is simply on the record for other gemologists who may examine the diamond later.

What Is Diamond Clarity Haze?

Since clarity grading is limited to 10X magnification characteristics beyond that scrutiny can go unreported. Undisclosed diamond haze is caused by large clouds of microscopic pinpoints when they become dense enough to interfere with light transmission and reduce transparency.

What Are Sleepy Stones?

Trade members may refer to hazy diamonds as being “sleepy stones,” a phenomenon which occurs on a sliding scale. Slight cases may not even be noticed by the average jeweler. In moderate cases the diamond will seem to need a cleaning when seen in some lighting environments. In the most severe cases the diamond is notably reduced in its performance qualities in all lighting environments.

How To Choose The Right Diamond Vendor?

*PriceScope Priceless Tip: For risk-free purchases, generous policies and robust consumer protection, consult our list of 5-star PriceScope Vetted Vendors.

As the world’s largest diamond and jewelry community, PriceScope is a place where many would like to advertise and list products. Few meet our standards. PriceScope Vetted Vendors provide safe online purchase experiences with generous inspection periods, hassle-free returns, and standout long-term benefits for clients.

Who Are Trusted PriceScope Diamond Vendors?

PriceScope’s Vetted Vendors meet or exceed PriceScope’s rigorous requirements for truthful advertising, best business practices, and proactive consumer protection. They deliver the high-quality customer service standards developed by over 100,000 PriceScope members over the past 20 years.

How Do We Assess Our Recommended Vendors?

We take the trust of our members very seriously – to protect our diamond and jewelry community, each of our potential associations involve a thorough vetting process. This often takes more time and effort, but it helps ensure the vendors who meet our requirements are the most consumer-friendly, setting industry benchmarks in truthful advertising, best business practices and consumer protection.

What Principles Do We Stand By For Our Vendors?

Components we have considered include, but are not limited to: Company history, including founders/owners, reviews/ratings and references. Truthful advertising, including messaging philosophies, proper promotion of strengths, proper use of terminology and industry esprit de corps. And best business practices and consumer protection through product selection, information provision, education, policies and short, mid and long-term client experience.

Do I Need A Diamond Certification?

*PriceScope Priceless Tip: Make sure your diamond comes with a grading report from the GIA, IGI, AGS or GCAL.

What Is A Diamond Certification?

Diamond Certificates (or grading reports) are issued by an independent gemological laboratory, following a secure, standardized diamond grading process. It’s an assessment of the diamond’s 4Cs, which are used to establish its value.

Who Is The GIA?

The GIA is the most widely recognized gemological institute, considered the world’s foremost authority on diamonds, colored stones, and pearls. A public benefit, nonprofit institute, the GIA has been the leading source of knowledge, standards, and education in gems and jewelry.

Who Is The IGI?

The IGI is the world’s largest gemological organization, operating 18 laboratories and 14 schools of gemology around the world. In addition to being the world leader in lab-grown diamond grading IGI issues grading reports for finished jewelry, serving more consumers than any other lab.

Who Is The AGS?

The AGS began grading diamonds in 1996 and is best known for their strict cut and performance standards. The AGS Platinum Report is the certificate of choice for diamond brands renowned for superior cut quality. They are one of two top-tier laboratories offering cut quality assessments for certain fancy shapes.

Who Is The GCAL?

The GCAL, established in 2001, is the only laboratory issuing diamond “certificates” backed by a guarantee. The GCAL focuses on diamond cut analysis, using a copyrighted diamond-specific performance assessment method, and provides a unique diamond fingerprint known as Gemprint. They are one of two top-tier laboratories offering cut quality assessments for certain fancy shapes.

How Do Standards Vary Across Certifications?

Generic reports accompanying economical pieces like those seen in mall or department store jewelry counters should not be confused with loose diamond certification (or grading reports). These documents are not item-specific, they are mass-produced to describe a production run of numerous similar pieces. They are not nearly as strict, accurate or expensive as stand-alone diamond grading reports or jewelry identification reports, prepared for a specific piece.

Is Carat Weight Universal?

Yes. Diamond grading scales are calibrated to three decimal places. Most laboratories establish carat weight to two decimal places, with the exception of the AGS, which reports to three.

How Are Color and Clarity Grades Certified?

Diamond color employs the alphabet, starting with D (colorless) and progressing from E to Z as the presence of tint increases. Diamond clarity uses a set of acronyms in a diamond ratings system which is not as intuitive as color and clarity. The grades are subjective decisions made by trained gemologists examining the stones.

How Are Cut Grades Certified?

Diamond cut grading is treated differently from lab to lab. Why? Because color and clarity have been strictly graded since the 1950s, but the world’s largest laboratory, the Gemological Institute of America (GIA), didn’t grade cut until 2006. By then, other diamonds ratings systems for cut had been launched by other laboratories. As a result, there are a number of different approaches to grading cut.

What Is Diamond Standard Deviation?

No two diamonds are alike. Color and clarity occur on a sliding scale and a diamond sitting directly on the border of two grades may come out on one side of the other, depending on the subjective opinion of the gemologist making the judgment. To that end, a standard deviation of +/- one grade is generally deemed acceptable among professionals.

What Is An Under Graded Diamond?

Under grading occurs when a jewelry professional intentionally claims a diamond has lower grades than it would normally receive according to strict, industry-accepted international standards. The goal of intentional under-grading is to win consumer business by creating fear-based doubts about other professionals.

Is It Worth Buying A Certified Diamond?

Any diamond of value should be accompanied by a grading report from a top-tier laboratory. Expensive jewelry pieces should either be accompanied by a finished jewelry grading report or, at minimum,  come with a grading report describing the central gemstone. For inexpensive pieces, full grading may not be practical.

How Much Does A Diamond Certification Cost?

Laboratory analysis and grading charges are largely based on the diamond’s carat weight. For a one-carat loose diamond, the charge has historically landed near $100. There are many services offered by the different grading laboratories. Consumers may contact them for full explanation of services and fees.

Are Diamonds Certified The same?

Presuming you stay with certification from a top-tier diamond certification laboratory, diamond ratings for color and clarity will typically remain within one grade for any specific diamond. Considering how granular and subtle those diamond ratings systems are, a one grade difference is technically negligible. Of course, those values are used to establish a diamond’s value so it’s in the best interest of shoppers to use the strictest set of grades.

How To Take Care Of Your Diamond?

*PriceScope Priceless Tip: Do not expose gemstone jewelry to mechanical cleaners. Learn our Seven Steps to Sparkle.

Your jewelry was designed to be worn. Frequently and proudly. You will be able to keep your jewelry in top condition by learning How to Clean Jewelry.

Should I Clean My Diamond Regularly?

Yes. Each day, before retiring follow this Careful Cleaning Credo: Remove all jewelry and wipe each piece down with a clean soft dry cloth to remove perspiration, chemicals, etc. This prevents buildup and helps maintain optimum beauty between professional cleanings.

Should I Insure My Diamond?

Engagement Ring Insurance is a personal decision, but diamond is the hardest material known to man, but even the most flawless diamond can chip if struck along its crystal’s cleavage plane. For this reason, we believe every diamond owner should carry insurance.

Should I Get My Diamond Inspected Regularly?

Yes. Enlist the help of a professional jeweler every so often to deep-clean and check integrity. How frequently depends on your wear habits – as a general rule we recommend once or twice per year.

How To Bring Back The Diamonds Sparkle?

Periodically it’s prudent to perform thorough home jewelry cleaning. Due to their superior hardness, toughness, and stability, there is a seven-step process that can be safely performed with diamonds. Other jewelry should be considered on a case-by-case basis.

How To Prevent My Diamond From Getting Cloudy?

Clean the bottom of the diamond regularly with a soft brush. Light enters the stone from above, but the bottom facets play a critical role in both reflection, which helps the stone be bright, as well as refraction. Light that would normally reflect gets drawn out by grease or oil on the underside. This mutes how diamonds and gemstones sparkle.

Should I Use A Professional To Clean My Diamond?

If you clean your diamond and gemstone jewelry after each use according to this credo, and additionally clean daily-wear jewelry using these careful seven steps once per week your visits to a professional will be less frequent. Nevertheless, for deep cleaning we recommend visiting your jewelry pro once or twice per year.