Diamond Clarity Explained: What is VS1, SI1 & Why It Matters

Posted on July 16th, 2025

 

Diamonds might be sparkly, but figuring them out? Not always so clear.

Clarity, in particular, sounds like something lifted from a lab report—but hang on, it’s got more personality than that.

Every diamond has its quirks, kind of like people. Some are practically flawless; others come with tiny “birthmarks” that tell a story.

These marks don’t ruin the sparkle—they give it character. And no, you don’t need a microscope to start caring.

Once you get a feel for how clarity fits into the bigger picture, you'll see why those little flaws are a big deal.

Now, let’s talk VS1 and SI1—two clarity grades that get tossed around like secret codes at a jewellery counter.

They might sound technical, but they’re part of a much more relatable game: balancing what your eyes love with what your wallet can handle.

These grades help decode what’s going on beneath the surface, without losing sight of what matters most—how that diamond makes you feel. You’re not buying a lab score; you’re choosing a piece of you.

Clarity just happens to be one of the juiciest plot points in that story.

 

How To Read Diamond Clarity Charts

Reading a diamond clarity chart shouldn't feel like decoding ancient runes.

It's actually a handy roadmap that helps you figure out what’s really going on inside that glittery little rock. These charts lay out clarity grades from top-tier Flawless (FL) and Internally Flawless (IF), all the way down to Included (I1, I2, I3).

Somewhere in between, you’ll find the sweet spot: Very, Very Slightly Included (VVS), Very Slightly Included (VS), and Slightly Included (SI). Sounds like alphabet soup, but here’s the deal—clarity is all about the imperfections a diamond carries.

Inclusions (internal quirks) and blemishes (external marks) are what graders zoom in on under 10x magnification to determine where the stone lands on that scale.

Now, does a Flawless grade mean you’re getting a dramatically sparklier stone? Not always.

Some diamonds with lower clarity grades—like SI1—can still shine just as bright because many inclusions are so tiny, your eyes won’t notice them without a jeweller’s loupe.

The key is how these imperfections interact with light. If they block or disrupt the sparkle, that’s where clarity matters.

But if they’re tucked away on the edges or only visible under a microscope, you might just score a better deal without sacrificing much in the looks department.

Here’s where things get juicy: VS1 vs. SI1. A VS1 diamond has tiny inclusions that are hard to find even under magnification, while SI1 diamonds may show more obvious marks—still not glaring, but easier to spot with the right tools.

Both grades are popular because they’re visually impressive without diving into the Flawless price tier. That means more wiggle room for other features you might care about, like size or setting style.

Most clarity charts include diagrams showing where the inclusions are located—kind of like a treasure map, except the X marks the specks.

This helps you decide what you can live with and what might bug you every time the light hits it just wrong. Because let’s be real: diamonds aren’t just about perfection—they’re about personality.

And knowing how to read these charts lets you choose a stone that fits yours.

So, before you get dazzled by a sales pitch or hypnotised by a price tag, clarity charts offer a grounded way to compare apples to shiny, sparkly apples.

 

Comparing VS1 and SI1 Diamonds

Now that you’ve got a handle on how clarity charts work, it’s time to zoom in on two grades that get a lot of attention—VS1 and SI1.

Think of VS1 (Very Slightly Included) as that student in class who never gets called out—sharp, quiet, and nearly perfect under pressure.

Inclusions in a VS1 diamond are tiny and typically tucked away, barely detectable even under 10x magnification. To the naked eye? You’re unlikely to see anything at all.

These diamonds hit a sweet spot: noticeably clean, but not priced into the VVS stratosphere. That makes VS1 a favourite for buyers who want high visual purity without going full perfectionist—or bankrupt.

Now, SI1 (Slightly Included) plays a different game. Still respectable, still beautiful—but it’s the friend who doesn’t mind showing a few quirks.

Inclusions here are more visible under magnification and sometimes even without it, depending on their position and size.

But here’s the kicker: in many cases, those inclusions can be hidden beneath prongs, blended into a clever setting, or just plain overlooked unless you’re obsessing with a loupe.

If your eye’s more on size or sparkle than on scientific purity, SI1 can offer a lot of bang for the buck. It’s often the go-to for those who’d rather invest in a larger stone or superior cut and still walk away with something stunning.

The real difference comes down to priorities. VS1 gives peace of mind to clarity-focused buyers—people who want minimal distractions when admiring their diamond from every angle.

SI1, meanwhile, is a savvy choice for those who know where to look for value and aren't rattled by a tiny flaw here or there.

These grades sit close together on the clarity scale, but their real-world impact can feel worlds apart, especially when paired with the right setting, lighting, or design.

Ultimately, deciding between VS1 and SI1 is less about perfection and more about perspective. Are you the type who leans toward immaculate detail, or do you embrace a little character if it means upgrading carat or cut?

There’s no wrong move—just a better fit for your taste, budget, and what you want that diamond to say about you. Because at the end of the day, it’s not just about what’s inside the diamond—it’s about what it reflects.

 

Choosing the Best Clarity for Engagement Rings

When hunting for the perfect engagement ring, clarity isn’t the only thing worth squinting at—but it definitely deserves a closer look.

Choosing between VS1 and SI1 isn’t just about playing detective with a jeweller’s loupe. It’s about figuring out what matters most to you and how that diamond will play its part in the story you're telling.

Sure, VS1 diamonds are polished charmers—nearly flawless to the naked eye, bright, clean, and totally traditional.

But SI1 diamonds? They’re the smart spender’s secret weapon: beautiful to look at, just a little more approachable on the price tag, and full of potential when paired with the right setting.

Here’s where a little strategy comes in. Choosing SI1 over VS1 doesn’t mean settling; it means shifting your focus.

That extra wiggle room in your budget can be put to very good use:

• Upgrade to a larger carat size that brings serious finger presence

• Choose a custom or more detailed setting that shows off your style

• Prioritize an excellent cut to maximize sparkle, even with minor inclusions

When set well, many SI1 inclusions disappear into the background, especially if they’re tucked beneath prongs or near the edges.

If you’ve got a sharp eye for design—or a bold vision—SI1 gives you creative freedom without the pressure of perfection.

You’re not just buying a diamond; you’re crafting an entire look. And often, that "less-than-flawless" stone becomes the centrepiece of something far greater.

Clarity is personal. Some folks want nothing less than visual purity; others don’t mind a few quirks if it means more dazzle elsewhere.

If you know you’ll be staring at your ring every day and that one tiny mark will drive you nuts, then sure, VS1 may be worth it.

But if you’re more concerned with how the diamond shines in the real world—and you trust your jeweller to help you spot a well-placed inclusion—then SI1 could be your match made in sparkle heaven.

Ultimately, clarity isn’t about chasing perfection; it’s about setting your priorities. Every inclusion tells a story, every sparkle has a source—and the best diamond for you is the one that reflects both your values and your vision.

 

Discover The Brilliance Of Si1 Clarity Firsthand With Jewellry From NLG Jewellers Limited

As you wrap up your exploration of diamond clarity, one thing becomes crystal clear: it’s not just about the grade—it’s about finding a stone that resonates with your story, style, and budget.

No matter if you’re drawn to the clean, classic appeal of VS1 or intrigued by the smart balance of value and beauty offered by SI1, clarity is a reflection of your personal priorities, not just a number on a chart.

Inclusions aren’t flaws—they’re fingerprints of nature, adding depth and individuality to your diamond.

For those seeking a perfect harmony of elegance and affordability, explore our 18K Yellow Gold Diamond Ring – 1.02 ct F Colour, SI1 Clarity, a stunning example of how SI1 clarity can deliver serious sparkle with impressive value.

At NLG Jewellers Limited in Hatton Garden, we specialise in pieces that honour your milestones without compromising your vision. Our collection blends quality, design, and price with a focus on helping you make informed, meaningful choices.

Ready to start your journey or want advice on choosing the right diamond? Contact us today or give us a call at +44 7956 536856.

We’re happy to answer questions, offer insight, or help you find the piece that perfectly reflects your personality and goals.

With NLG Jewellers, it’s never just about jewellery—it’s about capturing a moment, telling your story, and owning your sparkle, one carefully chosen diamond at a time.