If you’re shopping around for a loose diamond at a nearby jewelry store or online diamond dealer, ask your dealer for a 10X loupe with which you can closely examine the interior of the diamond. And, if you intend buying loose diamonds privately, it would be better if you bought a 10X eye loupe directly from a jewelry house. In fact, the best eye loupe you can buy is the Hastings 10X Triplet eye loupe from Bausch & Lomb. The best way to check a diamond for clarity is with a stereoscopic binocular microscope which comes with dark field illumination.
As you perhaps know, all loose diamonds are given a clarity grade below a power of 10X. When you examine a loose diamond with the help of a loupe, bring it all the way up to your eye and then very gradually pick up the diamond with tweezers to a point just below the loupe so that you see it clearly at close range. Pick up the diamond with the help of tweezers by placing the diamond table down. Now, set the diamond firmly within both sides of the tweezers.
Once you’ve examined the diamond closely through the table, check the side of the diamond to check for its girdle or border that separates its crown or top from its pavilion or bottom section.
Often, you may find that a loose diamond is graded SI-2 for clarity. It’s necessary you know both the nature and the location of the inclusions that the loose diamond under examination possesses. Just to be absolutely sure, examine these inclusions under the loupe or under the microscope yourself. With the jeweler’s help, check the color of the diamond against a master comparison set that has already been color graded by the Gemological Institute of America.