The Complete Guide to Shopping Loose Round Diamonds

guide to shopping for loose diamonds

People spend weeks--sometimes even months--pouring over different diamond shapes, settings, styles, and price points, all while hoping to find something that encapsulates their love for their future spouse. Sometimes, however, that perfect ring is harder to find than you’d think.

These days, more and more people are choosing to customize their wedding or engagement rings. This means they purchase a loose diamond, then find a retailer that does custom design work to create the ring they’ve been dreaming of. Seems simple enough right?

Buying a diamond engagement ring this way can be an exciting, creatively fulfilling process. However, there are a few things you should keep in mind as you shop for a loose round diamond which we've outlined below. If you're interested in loose diamonds as an investment, then be sure to check out our guide to buying loose diamonds as investments.

Your Budget & Loose Round Diamonds

Most people assume that a loose diamond is less expensive than a completed ring. Sometimes, this is true; after all, you’re only purchasing a center stone, not the extra diamonds or the metal band. However, buying a loose diamond means that you choose from any number of quality combinations, making it easy for the loose diamond to be just as, or more, expensive than a set ring. Added to the cost of a custom setting, you could end up with a ring well beyond your budget! It's helpful to set two budgets when shopping this way, one for the diamond and one for the setting.

That being said, the range of quality with loose diamonds is a colossal selling point. With a high-quality diamond, even smaller carat sizes look incredible--round cut diamonds, with their 58 facets built to capture the light, are a great choice for those looking for a cost-effective small stone. On the other hand, round diamonds are forgiving, and you may opt for a lower quality than what's found in a preset ring and get a larger stone. Keep aware of your spending limit and you'll be sure to find the perfect diamond.

Your Budget & Loose Round Diamonds

The 4C’s & Round Diamonds

gemologist inspecting stones

So let’s say you’ve made the decision to buy a loose, round cut diamond. You’ve jumped the first hurdle (choosing a diamond shape) and you’ve made a great choice--round cuts account for over 75 percent of diamonds sold each year worldwide. Now comes your next challenge: inspecting countless diamonds and finding the right stone for you.

The diamond you select should be the one you think is the most beautiful (and the one you think your intended will adore), but some shoppers can be overwhelmed by the selection placed before them. How do you know which one is best? Thankfully, there are a few guidelines that can help you determine which diamond has the greatest value.

A diamond’s value is based on a number of factors, like its depth, table, color, and clarity, that are summarized by the Four C’s of Cut, Color, Clarity, and Carat.

Round Diamond Depth

The depth (how long the diamond is from top to tip) and table (the size of the flat part at the top) of a diamond determines how light is reflected in the stone. These factors along with a few other characteristics go into determining the cut of the diamond.

Round Diamond Depth

Round Diamond C's

Color and clarity are a bit more self-explanatory - gemologists determine color by comparing the stone’s color to set standards. They review clarity by looking at a diamond under 10x magnification, inspecting it for blemishes and inclusions.

Round Diamond C's

For the ideal round cut diamond, you should look for a depth that measures between 58 and 64 percent and a table that measures between 53 and 64 percent of the diamond’s diameter (the measurement from one side to another). In this range, light bounces off the diamond’s facets and reflects back at you, creating that beautiful fiery sparkle we all admire. Cut should never be sacrificed for  round diamonds.

Color and clarity are more subjective, but most gemological labs do grade diamonds to guide shoppers to the best stone. A diamond that is ranked FL or IF is the highest grades for clarity. For color, diamonds receive letter grades from D to Z. Round diamonds disperse color and hide inclusions, so you can be flexible here. For a white and eye clean stone, stay at an I color or higher and an SI1 clarity or better.


close up of a round loos diamond

Loose Diamonds & Certification

As you shop for your round diamond, it’s important to check for certification, as well as diamond quality. What is a diamond certification? Simply put, it’s an official “stamp of approval” from a third-party gemological lab that indicates the diamond is exactly as it’s said to be. A diamond certification will provide you with a scientific blueprint of the diamond’s properties and will mention if the stone has been treated or enhanced. This is important for someone buying a loose diamond; if you are on the hunt for a gorgeous stone, you’ll want that stone to be the genuine article.

There are four major labs that issue diamond certifications: GIA, the Gemological Institute of America; AGS, the American Gemological Society, EGL the European Gemological Laboratory; and IGI the International Gemological Institute. Each of these labs offers different grading methods, but they are generally agreed upon as reliable sources for diamond certification.

Loose Diamonds & Certification

When shopping, be sure to inspect the round diamond yourself in different lighting. Most jewelers use bright, fluorescent lighting in their shops, making their stones very sparkly, but can hide imperfections. Ask to see the stone in natural light before you commit to your purchase. If you are shopping online, ensure that there is an exchange policy that gives you the chance to view the stone in person and return it if it doesn’t meet expectations.

If the store or online retailer offers expert guidance, take advantage of it, but beware if they try to push you outside of your comfort zone. By the time of purchase, you should feel confident that your diamond has been approved by you and the gemologist. That’s the best way to ensure approval from your bride-to-be!

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