How to Tell if a Diamond is Good Quality: A Simple Guide for First-Time Buyers

If you’re the type who likes to do a little homework before stepping into the showroom, we’ve put together a quick diamond quality guide to help you feel more confident.
Loose aquamarine and cushion cut diamond gemstones displayed in front of Ethan Lord Jeweler ring box

If you’ve never shopped for a diamond before, don’t worry, you’re not alone. Most people don’t know much about diamonds going into their first appointment, and that’s completely okay. That’s what we’re here for.

The 4 Cs of Diamond Quality

When jewelers talk about diamond quality, we usually reference the 4 Cs: cut, color, clarity, and carat. These are the key factors used to evaluate a diamond's value and appearance.

Here’s what each one means (in simple language):

1. Cut: The Sparkle Factor

Of all the Cs, cut has the biggest impact on how much your diamond sparkles. This doesn’t refer to the shape (like round or oval), but how well the stone has been faceted to reflect light.

If you’re looking for the best diamond cut for sparkle, a round brilliant cut is your best bet, it’s engineered for maximum light return. But many fancy shapes (like oval, pear, or radiant) can also offer serious shine when well cut.

2. Color: From Colorless to Warm

Diamond color is graded on a scale from D (completely colorless) to Z (noticeably yellow or brown). Most engagement ring diamonds fall somewhere in the D–J range.

  • D–F: Colorless (very rare and highly valued)

  • G–J: Near colorless (still bright and beautiful, often better value)

  • K and beyond: Visible warmth or tint

Your choice depends on your personal preference and setting style. Yellow gold, for example, can make slightly warmer diamonds appear more neutral.

3. Clarity: Fewer Flaws, More Value

All diamonds have natural imperfections called inclusions or blemishes. Diamond clarity measures how visible those are under magnification.

The scale ranges from Flawless (FL) to Included (I1–I3). That said, many inclusions are invisible to the naked eye, so clarity is often the best place to save a little without sacrificing beauty.

Pro tip: Look for diamonds rated VS1–SI1 for great balance between clarity and value.

4. Carat: Size, But Not the Whole Story

Carat weight refers to how heavy the diamond is, not necessarily how big it looks. Two diamonds with the same carat weight can appear very different depending on cut and shape.

Focus on overall look, not just carat number. A well-cut 1.0 carat diamond can shine brighter and look larger than a poorly cut 1.2 carat.

Other Factors to Consider

Beyond the 4 Cs, here are a few extras to keep in mind when learning how to buy a diamond:

  • Certification: Always choose a stone that comes with a grading report from a trusted lab, like GIA or AGS.

  • Fluorescence: Some diamonds glow under UV light. This doesn’t affect all diamonds the same way, ask to see it in person if you’re unsure.

  • Your setting: A good setting can enhance or downplay color, make a stone appear larger, or protect a slightly included diamond. It’s also important to select a wedding band that compliments both the engagement ring and stone.

You Don’t Have to Know Everything

At the end of the day, a diamond quality guide is just that, a guide. You don’t need to be an expert to choose a beautiful, meaningful ring. You just need someone who can walk you through the options, answer your questions honestly, and help you compare stones side by side.

And if that’s something you’re looking for, we’re always happy to help

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