Before buy Jewelry better to read guidance at below from “costco.co.uk Diamond & Jewellery Guide”. check this out
Diamond Quality & Colour Scale
Diamond Education: The 4 C’s
Costco makes purchasing the highest quality diamonds easy by offering only the industry’s highest quality diamonds at the lowest possible price. Our long-standing relationship with our suppliers guarantees we get the best selection at the best value. Costco’s experienced buying team works with our suppliers evaluating and hand-selecting each diamond for its quality and brilliance. Our gem laboratory or an independant laboratory then inspects every diamond to ensure it meets the strictest quality standards in the industry in carat, cut, colour and clarity. You can be confident your purchase is as special to us as it is to you.
These items come with a Summation Of Appraisal certificate from the International Gemological Institute (IGI) or a Safeguard certificate. This is to certify that the item described above is genuine, and has been independently examined in the laboratories of IGI or Safeguard .
Also included with these diamonds is a GIA (Gemological Institute of America), Gem Trade Laboratory, Diamond Grading Report. Gem Trade Laboratory is a division of GIA Enterprises, Inc., a wholly owned subsidiary of the nonprofit Gemological Institute of America, Inc. This describes the characteristics of the diamond at the time of the examination based upon 10x magnification.
Costco makes purchasing pearls simple and easy by offering only the industry’s highest quality pearls at the lowest possible price. Because there is no standardised grading system for pearls, Costco does not list grades on our pearl items. However, all of our pearls are inspected by the gem and pearl laboratory. Costco is able to ensure that the pearls have no obvious blemishes, have good lustre, and that the shape, colour, and sizes of the pearls match where applicable. Whether you are looking for Akoya Cultured, Freshwater, South Sea or Tahitian, Costco.co.uk has what you need.