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Finding the Perfect Diamond
with Rio Diamond Source
Rio Diamond Source is your personalized service to help you find the perfect diamond for your customers. If we don't have the perfect diamond in stock, we will source it—and answer any questions along the way.


Ordering a diamond less than 0.40 carats in size? Place your order before 4:30 p.m. MT and we will ship the same day. You must be a Rio-qualified diamond buyer to purchase diamonds.

Shop Rio Diamonds

Rio Diamond Source

Looking for a diamond larger than 0.40 carats?

Need help using the 4Cs to select the diamond that fits within your budget?

Talk to one of our Graduate Gemologists—we're happy to help.

Become a Rio-qualified Diamond Buyer

You must be Rio-qualified in order to purchase loose diamonds from us. Becoming certified is simple. Meet one of the following criteria:

  • • If you are a member of the Jewelers Board of Trade, you automatically qualify,
  • • Provide us with a current copy of your business license and two invoices or statements from another supplier in the jewelry industry.
  • • Be a student currently enrolled in a jewelry-making course who can provide either a letter from your instructor on school letterhead or a copy of your coursework transcript.
Qualify NOW

Buying Brilliance

Review Rio’s comprehensive Diamond Buyer's Guide and sizing chart to help you understand a diamond’s quality characteristics.

Buyers Guide
Review Rio's Diamond Sizing Chart

“The Rio Diamond Source team is made of friendly, able, dependable, helpful, professional experts. Shannon and Chris have always gone the extra mile, and then some, to help me find the perfect diamond for my clients. They always do an excellent job in helping me.”
—Hector, Customer since 2013

Pear Shaped Diamond

Featured Diamond: The Timeless Pear Shape

The pear-shaped diamond has increased in popularity and we are excited to offer a limited selection to our qualified customers.  These near-colorless diamonds range from 0.5-0.75 carat weight. Don’t miss your chance to add one of these sparkling treasures to your high-end designs!

Shop Now

“When I call for diamonds from Shannon, she knows how fussy I am, especially because I’m a stonecutter. She knows, after all these years—we have the same eye for stones. I have to over-quality my custom-order pieces to ensure I don’t get stuck with the bill.”
—Tim, Customer since 1991

“Rio bends over backwards to find what I ask of them. It was so nice to find a place that was respectful to us. I cannot tell you in words how professional Chris and Shannon are. Their selection is unbelievable—the service and the supply and the resources at Rio are just phenomenal. Anyone looking for a diamond anywhere in the country should go to you, in my opinion. You’re not going to find a better total package anywhere else. I can’t tell you how happy I am. Trust, intelligence and honesty all come together to make it a pleasant experience.”
—Terry, Customer since 2011

Rio Diamonds are 100% Conflict Free Logo

Rio Diamonds are 100% Conflict Free

Please know that every diamond you buy from Rio Grande is certified conflict-free. Rio has earned certification from the Responsible Jewellery Council, verifying that we are in compliance with the Kimberley Accord and that our stones, our supply chain and our facility meet the high standards of the RJC Code of Practices. Further, RJC routinely conducts audits to certify that we are maintaining these standards.

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Home > Remove gemstones and diamonds > Remove diamonds
4 results | 1 pages
GIA Diamond Color Grading Scale
The Gemological Institute of America created this scale of color and clarity grading for diamonds, and it remains the international standard.
How To
Diamond Grading at Rio Grande
In Rio Grande's Gemstone Department, diamonds of every grade are carefully examined and sorted so you get the quality stone you order.
Sizing Round Diamonds
Diamond sizes can vary, so use this reference chart to compare the range of carat sizing to millimeters for easier stone-setting.
How To
The Difference Between Carat and Karat
Here's a quick explanation of carat weight in gemstones versus the term karat, used in gold alloys.

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