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For questions regarding jewellery found on costco.co.uk, please email your question(s) to onlinediamonds@costco.co.uk
No. All items must be purchased through the website and are shipped directly to you.
No. All diamonds sold at costco.co.uk are sold as finished pieces of jewellery.
No, Costco does not provide any resizing services. However, most rings can easily be resized by a professional jeweler. Once resized rings cannot be returned.
The estimated delivery time for receipt of an item is listed on the website. To ensure our quality is never compromised and our orders are promptly fulfilled, we are not able to fast track shipments.
Coloured stone cutting is not an exact science. When listing a piece of coloured stone jewellery we guarantee a minimum millimitre size. Coloured stones are often bought and sold according to a calibrated millimitre size because carat weights can vary widely.
costco.co.uk shares the concern of the global community in abolishing conflict diamonds, and is committed to procuring goods of the utmost integrity. We are proud to sell beautiful, high quality diamonds that are obtained solely through closely monitored legal channels set forth by the United Nations' Kimberley Process.
Costco Article of Description
When you purchase an article of jewellery with a diamond of less than 1.00ct, you will receive an Article of Description written by one of our Gemologists, with a degree from GIA, detailing your jewelry piece.

GIA Diamond Grading Report
When you purchase an article of jewelry with a 1.00ct center diamond or larger, you will receive a Diamond Grading Report from the Gemological Institute of America (GIA) detailing and mapping the diamond.

Jewellery Grading/Gemological Report
When you purchase an article of jewelry with a 1.00ct center diamond or larger, it will also include a Jewelry Grading/Gemological Report describing the jewelry piece. This report will not have a monetary value listed, however, you can contact the company that issued the report and request an insurance appraisal. In this case your Costco purchase price will be documented as the insurance replacement value.

Hallmarking Gold Jewellery
Gold-only jewellery does not come with any type of paper authentication, such as a certificate or Article of Description, instead the item itself is hallmarked.
Although treating diamonds is an accepted practice among many jewellers, Costco sells only natural and untreated diamonds.
These are unique pieces hand-selected for their impeccable quilaity & brilliance. Due to this unique nature our range is constantly changing, to view our current selection search 'One of a Kind'