Confidence Guaranteed.
Certified Diamonds
When you shop for a diamond at Lewis Jewelers, you’re not just buying a gemstone; you’re investing in a promise. A promise of quality, integrity, and transparency. For decades, we’ve helped generations of couples and collectors find the diamond that’s just right for them, and certification plays a key role in that experience.
That’s why every loose natural diamond in our showroom is certified by one of the world’s leading gemological laboratories—most notably the Gemological Institute of America (GIA) and the American Gem Society (AGS). These organizations set the gold standard in diamond grading, ensuring that what you see—and what you fall in love with—has been evaluated using the most rigorous and respected criteria in the industry.
What Is Diamond Certification?
Think of a natural diamond certificate as your stone’s passport. It provides a detailed, unbiased report on the diamond’s key characteristics—its cut, color, clarity, and carat weight, also known as the 4Cs. Certified diamonds are graded under controlled conditions by trained gemologists using precise equipment. The result? You get a fully transparent look at the diamond’s attributes, helping you compare options with confidence and clarity.
At Lewis Jewelers, we exclusively offer independently certified natural diamonds—never self-graded stones. This ensures that every diamond we present to you meets industry-accepted standards and gives you a clear understanding of its beauty and value.
What Makes GIA Certification So Trusted?
Founded in 1931, the Gemological Institute of America (GIA) is a nonprofit organization that established the globally recognized 4Cs grading system and continues to be the leader in the field of gemological research and education. When a diamond is graded by the GIA, it means:
- The evaluation is unbiased and objective
- The grading process follows strict, repeatable standards
- The diamond’s report is recognized around the world
Every GIA diamond report includes a unique report number, often laser-inscribed on the diamond's girdle for easy identification. It details the diamond’s proportions, finish, fluorescence, and other technical details that influence its beauty and price.
For customers who are looking for ethical sourcing and complete peace of mind, a GIA-certified diamond offers the highest level of confidence available today.
Why Certification Matters
Buying a certified diamond protects your purchase and provides valuable documentation for insurance purposes. But just as importantly, it allows you to:
- Shop with clarity—you’ll understand exactly what you’re getting
- Compare apples to apples when choosing between diamonds
- Avoid overpaying for lower-quality stones that look similar at first glance
- Ensure authenticity with lab reports from independent, highly respected authorities
When you shop with Lewis Jewelers, our expert advisors will walk you through the grading process so you understand how each diamond compares—and what matters most for your goals, budget, and style.
A Personal Approach to Diamond Shopping
Beyond the 4Cs
While grading reports are essential, they’re only part of the story. A diamond’s presence—how it performs in light, how it looks on your hand, and how it connects to your personal style—can’t be fully captured on paper.
That’s why we take the time to sit down with you, show you your options in person, and explain the subtle differences that affect beauty and brilliance. We believe education is empowering—and there’s never any pressure. Our diamond advisors are non-commissioned, so the experience is always focused on what’s best for you.
One of Michigan’s Largest Certified Diamond Selections
With one of the most extensive inventories of loose GIA-certified diamonds in Southeast Michigan, Lewis Jewelers offers every shape, size, and quality to help you find exactly what you’re looking for—whether it’s a one-carat round brilliant or an eye-catching fancy shape with lab-grown or natural origins.
Prefer to start with the diamond and design the ring around it? We offer complete custom design services to bring your vision to life. Want to browse preset styles instead? We carry top designers like TACORI, Michael M., A.JAFFE, and more—all available in-store and online.
Schedule a Free Diamond Guidance Appointment
We get it—buying a diamond can feel like a big decision. That’s why we offer complimentary one-on-one Diamond Guidance Appointments to walk you through the process in a friendly, relaxed setting. No jargon. No pressure. Just honest answers and expert insight.
Visit us in Ann Arbor to explore our certified diamond selection in person—or browse online to get started. Need help narrowing down your options or understanding grading reports? We’re just a phone call or click away.
