Smart people go for buying high value items only from dependable sources, which can provide certification / guarantee for the quality of those products. And there are dependable sources wherein you can get certified items / goods / products, like certified diamonds.
While going in for such certified items might be slightly costlier, it is worth paying the premium because you are guaranteed of their quality and purity. www.brilliance.com is one such source for buying your certified diamonds at affordable price points.