In addition to shape, grinding and size, the most important attribute of a precious stone is its color. “Color diamonds are extremely beautiful forges of nature,” says David Warren from Christian’s auction house and adds “they are also much less frequent than white diamonds.” Accidental inclusion of the borone will make the diamond blue, a small change in structure, make it pink and the underground radiance turns green. Everything must be tested to ensure that colors are created by nature, not by man.
Warren recommends that GIA (Gemmological Institute of America) for diamonds and Swiss laboratories for other colored precious stones, “these laboratories have a best reputation”, he adds. For more information, visit http://www.christies.com/features/Collecting-guide-5-things-to-consider-when-buying-jewellery-6157-1.aspx