Diamonds can feel intimidating. There's a lot of terminology, a lot of grades, and frankly, a lot of money on the line. But here's the thing—once you understand the basics, you'll be able to walk into any jewelry store (or sell to any buyer) with confidence.
This guide covers everything from the famous"4 Cs" to insider tips that most people never hear. We've been buying and evaluating diamonds in the Tampa Bay area for over 25 years, and we're sharing what we know.
The 4 Cs: Your Diamond Scorecard
Every diamond is graded on four characteristics: Cut, Color, Clarity, and Carat weight. These were standardized by the Gemological Institute of America (GIA) in the 1950s and are now the universal language for describing diamond quality.
Think of them as a report card for your diamond. But here's the secret most jewelers won't tell you: not all Cs are created equal. Where you invest your money matters more than chasing perfection in every category.
Cut: The Most Important C
If you only remember one thing from this guide, let it be this: cut is king. A well-cut diamond will sparkle and dance with light, while a poorly cut diamond—even one with perfect color and clarity—will look dull and lifeless.
Cut refers to how well a diamond's facets interact with light. It's not about the shape (round, princess, etc.)—it's about the precision of the angles, proportions, and symmetry that determine how much light enters the diamond and how much returns to your eye as brilliance and fire.
Excellent
RecommendedMaximum brilliance. Light enters and reflects back beautifully. This is what you want.
Very Good
RecommendedNearly as brilliant as Excellent, often at a lower price. Great value choice.
Good
Reflects most light. Still attractive, but less sparkle than higher grades.
Fair
Allows light to escape. Noticeably less brilliant.
Poor
Light escapes from sides and bottom. Appears dull.
Insider Tip
When budget is tight, this is the last place to compromise. Drop a color grade, drop a clarity grade, even go smaller on carat—but keep that cut at Excellent or Very Good. A smaller, well-cut diamond will always look better than a larger, poorly cut one.
Color: The Absence of Color
Here's something that surprises most people: when we talk about diamond"color," we're actually measuring the lack of color. The most valuable white diamonds are completely colorless—like a drop of pure water.
The GIA grades diamond color on a scale from D (colorless) to Z (light yellow or brown). Why start at D? Because before the GIA system, graders used A, B, C, 1, 2, 3, and various other inconsistent scales. Starting at D eliminated any confusion with older systems.
Insider Tip
Here's where you can save serious money: G, H, and I color diamonds look colorless to the naked eye but cost significantly less than D-F grades. The difference is only visible when diamonds are compared side by side in controlled lighting. In a ring on your finger? You'll never notice. This is the smart buyer's secret.
Clarity: Nature's Fingerprints
Almost every diamond contains tiny imperfections—internal"inclusions" and external"blemishes." These formed billions of years ago when the diamond crystallized under extreme heat and pressure deep in the Earth. Think of them as nature's fingerprints—they make each diamond unique.
Clarity grades measure how visible these characteristics are under 10x magnification. The key word there is magnification—most inclusions are invisible to the naked eye.
FL (Flawless)
Eye Clean RareNo inclusions or blemishes visible under 10x magnification. Extremely rare—less than 1% of all diamonds.
IF (Internally Flawless)
Eye Clean RareNo inclusions, only minor surface blemishes under 10x. Also very rare.
VVS1-VVS2 (Very Very Slightly Included)
Eye CleanInclusions so slight they're difficult for even trained graders to see under 10x.
VS1-VS2 (Very Slightly Included)
Eye CleanMinor inclusions visible under 10x but characterized as minor. Not visible to naked eye.
SI1-SI2 (Slightly Included)
Usually Eye CleanInclusions noticeable under 10x. SI1 usually eye-clean; SI2 may have visible inclusions.
I1-I3 (Included)
Inclusions obvious under 10x and usually visible to naked eye. May affect brilliance.
Insider Tip
The sweet spot for most buyers is VS2 or SI1. These diamonds are"eye-clean" (no visible inclusions without magnification) but cost far less than VVS or IF grades. You're paying a premium for perfection you literally cannot see. Save that money for a better cut or larger size instead.
Carat: It's About Weight, Not Size
Here's a common misconception: carat doesn't measure how big a diamond looks—it measures how much it weighs. One carat equals 200 milligrams (0.2 grams), or about the weight of a small paperclip.
This distinction matters because two diamonds of equal carat weight can look very different in size depending on how they're cut. A well-cut diamond carries its weight in the top where you can see it. A poorly cut diamond may hide weight in a deep pavilion (bottom), making it look smaller face-up.
Approximate face-up diameter for round brilliant cut diamonds
The Price Jump Secret
Diamond prices jump significantly at"magic numbers"—0.50ct, 0.75ct, 1.00ct, 1.50ct, and 2.00ct. A 0.99ct diamond can cost 10-20% less than a 1.00ct diamond, but they look virtually identical. Same with 0.48ct vs 0.50ct. Smart buyers shop just under these thresholds for the best value.
Insider Tip
If you want maximum visual impact, focus on spread rather than carat weight. A well-cut 0.90ct diamond with good spread can look larger than a poorly cut 1.10ct diamond. Ask your jeweler about the diamond's measurements, not just its weight.
Diamond Shapes Explained
Shape is often confused with cut, but they're different things. Shape refers to the outline of the diamond—round, square, rectangular, etc. Cut refers to how well that shape has been executed.
Round brilliant is by far the most popular (about 75% of all diamonds sold), but"fancy shapes" have been gaining ground, especially for those wanting something more distinctive.
Round Brilliant
PopularThe classic choice. 58 facets engineered for maximum brilliance and fire. Most expensive per carat due to rough diamond waste during cutting.
Best for: Maximum sparkle, timeless appeal
Princess
PopularSquare shape with pointed corners. Second most popular. Excellent brilliance with a modern, geometric look.
Best for: Modern style, good value
Cushion
PopularRounded corners with larger facets that show off clarity. Has an antique, romantic feel. Very popular in engagement rings.
Best for: Vintage aesthetic, soft look
Oval
PopularElongated brilliant cut that makes fingers appear longer. Can show a"bow-tie" effect if poorly cut.
Best for: Larger appearance, flattering on hand
Emerald
Rectangular step-cut with cropped corners. Long lines create elegant"hall of mirrors" effect. Shows inclusions more easily.
Best for: Art Deco style, sophistication
Pear
Teardrop shape combining round and marquise. Versatile—can be worn point up or down. Flattering on the hand.
Best for: Unique style, elongating effect
Marquise
Boat-shaped with pointed ends. Maximizes carat weight for the largest face-up appearance of any shape.
Best for: Maximum face-up size
Radiant
Rectangular or square with trimmed corners and brilliant-style faceting. Combines emerald shape with round brilliance.
Best for: Brilliance in a rectangular shape
Asscher
Square step-cut with dramatic cropped corners. Creates a distinctive"X" pattern when viewed from above.
Best for: Art Deco, vintage glamour
Heart
Romantic shape requiring exceptional cutting skill for proper symmetry. Best in larger sizes where shape is clearly visible.
Best for: Romantic gesture, sentimental value
Insider Tip
Fancy shapes (anything non-round) typically cost 20-40% less per carat than round brilliants. This is because round cutting wastes more of the rough diamond. If you're flexible on shape, you can get significantly more diamond for your budget with an oval, cushion, or princess cut.
Diamond Certifications
A diamond certificate (also called a grading report) is an independent assessment of your diamond's characteristics. It's like a Carfax for diamonds—an objective third party examining the stone and documenting what they find.
Always buy certified diamonds. Without certification, you're trusting the seller's word on quality. Certificates protect you and provide documentation for insurance.
GIA (Gemological Institute of America)
Strongly RecommendedThe gold standard. Most consistent, most respected grading in the industry. GIA created the 4 Cs system.
AGS (American Gem Society)
Strongly RecommendedEqually rigorous as GIA. Known for their detailed cut grading system. Fully trusted in the industry.
IGI (International Gemological Institute)
AcceptableWidely used, especially for lab-grown diamonds. Generally consistent but sometimes grades more leniently than GIA.
EGL (European Gemological Laboratory)
Use CautionKnown for inconsistent grading, often 2-3 grades higher than GIA for the same stone. Be cautious.
Insider Tip
If you're comparing an EGL-graded diamond to a GIA-graded diamond, assume the EGL diamond is 2-3 grades lower than its certificate states. An EGL"F color, VS1" might actually be equivalent to a GIA"H color, VS2." This isn't a knock on EGL—just know what you're comparing.
Smart Buying Tips
Now that you understand the basics, here's how to put that knowledge to work. These are the strategies we'd tell a friend if they were shopping for a diamond.
Prioritize Cut Above All
A well-cut diamond will sparkle and hide minor flaws. Start with Excellent or Very Good cut, then optimize the other Cs within your budget.
Shop Just Below Magic Numbers
A 0.95ct diamond costs significantly less than 1.00ct but looks identical. Same applies at 0.50ct, 1.50ct, and 2.00ct thresholds.
G-H-I Color is the Sweet Spot
These grades look colorless to the naked eye but cost 15-30% less than D-E-F. The difference is only visible in lab conditions.
VS2 or SI1 Clarity Saves Money
As long as the diamond is"eye-clean" (no visible inclusions), higher clarity grades are wasted money. Always verify in person.
Consider Fancy Shapes
Non-round shapes cost 20-40% less per carat. If you're open to oval, cushion, or princess, your budget goes much further.
Always Buy Certified (GIA or AGS)
Never buy an uncertified diamond or one with lesser certifications. The certificate is your proof of quality.
See It In Person When Possible
Photos and videos can be misleading. Diamonds look different in natural light vs. store lighting. Trust your eyes.
Get an Independent Appraisal
Before major purchases, have an independent appraiser verify the diamond matches its certificate. This costs $50-100 but provides peace of mind.
Selling Your Diamonds
Whether you're selling an inherited piece, an old engagement ring, or simply want to convert diamonds to cash, here's what you need to know to get a fair deal.
Gather Your Documentation
Original certificates, receipts, and appraisals help establish value. No paperwork? That's okay—we can evaluate the diamond directly.
Understand Resale Value
Diamonds typically resell for 25-50% of retail price. This isn't because buyers are unfair—it's because retail markup is 100-200%. We offer fair wholesale value.
Get Multiple Quotes
We encourage you to shop around. A reputable buyer won't pressure you. If someone does, walk away.
Know What Affects Value
The same 4 Cs apply. Cut quality, color, clarity, and carat weight determine price. Certified diamonds with GIA/AGS papers command higher prices.
Consider the Setting
The metal setting has separate value. Gold and platinum are priced by weight and current market rates. We evaluate both diamond and setting.
Timing Matters Less Than You Think
Unlike gold, diamond prices are relatively stable. Don't stress about timing the market—focus on finding a trustworthy buyer.
Insider Tip
Larger diamonds (1 carat and above) with GIA certification and excellent cut grades hold their value best. Smaller diamonds and those without certification are harder to resell at good prices. If you're buying with potential resale in mind, invest in quality and documentation.
Frequently Asked Questions
What's more important: color or clarity?
For most people, color. Color differences in the G-J range are very subtle, but noticeable inclusions can be distracting. However, if you're choosing an emerald or Asscher cut (step cuts that show inclusions more), prioritize clarity.
Are lab-grown diamonds real diamonds?
Yes—they have the same chemical, physical, and optical properties as natural diamonds. The only difference is origin: lab vs. earth. Lab-grown diamonds cost 50-70% less but have lower resale value.
Why do diamond prices vary so much between stores?
Retail markup varies dramatically (100-300%). Also, not all certifications are equal—a"G color" from EGL might be an"I color" by GIA standards. Always compare apples to apples.
How can I tell if a diamond is real?
Home tests (fog test, newspaper test) are unreliable. The only sure way is professional testing with proper equipment. We offer free evaluations if you're curious about a stone.
Do diamonds appreciate in value?
Generally, no—at least not at the retail level. Diamonds are not investments. Buy them because you love them, not as financial assets. Exceptional stones (large, rare colors, historically significant) are the exception.
What's the difference between cut and shape?
Shape is the outline (round, princess, oval). Cut is how well the facets are angled and proportioned to reflect light. You can have a round shape with an excellent cut or a poor cut.
Have Questions About Your Diamond?
Whether you're looking to buy, sell, or simply understand what you have, our experts are here to help. Free evaluations, no pressure, honest answers.