There aren't just 4 C's when buying diamonds.

The diamond industry has done a good job driving its 4-C's when buying diamonds:

Color, Clarity, Cut, Carat weight.

But there is a fifth C -- Confidence in your jeweler.

Unless you're a graduate of the GIA or unless you have years of experience, can you really tell the difference between a D or an E diamond? Can you count the flaws in the stone or even know if the cut was correct for the correct angles? What's an S-1 and what's an S-2 stone?

This is why the fifth C, C for Confidence in your jeweler is so important. And this is why getting a recommendation from a friend or relative is important, checking reviews, checking an online reputation, and walking into the jeweler's store or back office and seeing diplomas can also help you make your decision.

And let's not forget the sixth C and that would be Comparison shopping.

Color
Cut
Clarity
Carat weight
Confidence in the jeweler
Comparison shopping

My 6-Cs for buying a diamond.