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Jewelry FAQS

Jewelry Education

Diamond Quality Information

The Gemological Institute of America (GIA) is the world's foremost authority on diamond and gemstones. GIA has established the internationally accepted standard for diamond grading on which Costco's standards are based.

Costco offers our members high quality jewelry at an exceptional value. Our team of GIA Graduate Gemologists inspect every diamond to ensure it meets Costco's strict quality standards. We only sell natural and untreated diamonds.

GIA Anatomy of a Diamond

Anatomy of a Diamond

GIA 4Cs of Diamond Quality

GIA Color Scale

GIA Color Scale

GIA Clarity Scale

Flawless Internally Flawless VVS1 Very Very Slightly Included VSS2 Very Very Slightly Included VS1 Very Slightly Included VS2 Very Slightly Included

GIA Cut Scale

Carat Weight

All diamond images and diagrams are for reference only and may not reflect true diamond quality grades or carat weight. Images are not for use in diamond grading.

Diamonds The 4Cs of Diamond Quality

Every diamond is a miracle of time, place and chance. Like snowflakes, no two are exactly alike.

Until the middle of the twentieth century, there was no agreed-upon standard by which diamonds could be judged. GIA created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut, and Carat Weight. Today, the 4Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world.

GIA Diamond Color and Clarity.

Costco Diamond Color & Clarity Guarantee

Costco Diamond Quality Guarantee. All diamonds supplied by Costco are as follows: Clarity to be VS2 or better, color to be I or better as outlined above on the Industy Grade Guide.

One-of-a-Kind Collection

Please see our exclusive collection featuring One-of-a-Kind high quality diamonds offered in various shapes and sizes.


  • Costco Article of Description - A detailed article of description will accompany diamond items with center stones less than 1.00ct.
  • Gemological Institute of America (GIA) Diamond Grading Report - All items with a 1.00 carat or larger diamond center stone will include a GIA Diamond Grading Report detailing the center diamond.
  • Gemological/Jewelry Report - All items with a 1.00 carat or larger diamond center stone will also include a Gemological/Jewelry Report describing the article of jewelry. This report will not have a monetary value listed. You can contact the company that issued the report and request an insurance appraisal, in which case your Costco purchase price will be documented as the insurance replacement value.
How to Read a GIA Grading Report.

Care and Maintenance

Although diamonds are one of the hardest substances on earth, they are still vulnerable to damage such as abrasion, chipping and breakage. We recommend having your jewelry inspected every 6 months by your local qualified jeweler for any needed maintenance or repair, avoid all harsh chemicals, such as chlorine or ammonia, as they may damage the metal and/or stones.

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