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FAQs about Certified Diamonds


Diamond jewelry is an investment, so it's important to make sure you get what you pay for. Certified diamonds are popular because you'll know that you're getting the best diamond in your price range. Several laboratories in the diamond jewelry industry are trusted sources in certified diamonds; each follows a number of set guidelines for certifying and rating diamonds. Here are the answers to the most frequently asked questions about certified diamonds.

Certified Diamond Questions:

  1. What is a certified diamond?
    Certified diamonds are rated in four categories, which are commonly referred to as "the four C's." Experts scrutinize diamonds and determine the stone's value based on the four categories. After the rating system is complete, diamonds receive registry numbers or have their branding numbers engraved on them upon request of the buyer.

    The Four C's of Certified Diamonds:

    • Clarity: Gemstones have naturally occurring flaws, also called inclusions. Clear diamonds have fewer inclusions and are more valuable. Diamonds can be flawless, meaning the stone has no external or internal flaws. These diamonds are incredibly rare and valuable. Most nice diamond jewelry features slightly included or very slightly included diamonds.

    • Color: Color is graded on a scale ranging from D to Z. Colorless diamonds are extremely rare and are awarded a rating of "D." Diamonds graded "E" through "H" are also valuable and beautiful because their color variations can only be detected by an expert. Diamonds with "I" and "J" ratings may have a slight yellow hue but are still beautiful. Diamonds rated "M" through "Z" have a yellowish hue. Some diamonds are actually valued for their color, including yellow, pink, brown, and blue diamonds. These diamonds are called "fancy diamonds" and are mainly rated based on their color intensity.

    • Carat: This is the weight of the diamond, but it may not actually reflect the stone's size, as diamond shape plays a role in size.

    • Cut: Cut has a lot of influence on the diamond's overall rating. Cut refers to both the shape of the stone and the quality of the cut. An excellent diamond cut will allow light to pass through the stone just right to make it sparkle brilliantly. Less-than-perfect cuts may have facets that are too deep or too shallow, causing the stone to have less brilliance.

  2. Which diamond certification institutes can I trust?
    Many companies and institutes certify diamonds. The American Gem Society Laboratories, also known as AGSL, is one of the most reputable organizations that certify diamonds. The AGS is based in Nevada and was founded in 1934. The Gemological Institute of America, also known as GIA, is also a trusted diamond certifier. The GIA was introduced in Los Angles in 1931. If you choose a different certification institute, be sure to research the organization thoroughly and check for signs that they are financially invested in your diamond jewelry decision, which may impact their rating.

  3. Should I consider treated and enhanced diamonds?
    That depends on your personal preferences. Diamonds can be treated with lasers to remove flaws, filled with sealant to fill fractures, or undergo color treatments. Enhanced diamonds can look just like a gorgeous natural diamond when viewed with the naked eye, but they are often much more affordable. Some jewelry lovers prefer knowing that their diamond is all-natural, while other people love getting seemingly flawless diamonds at a discount. You can learn more in our guide on diamond clarity enhancements.

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Updated January 8, 2015