Over the course of my thirty years in the diamond business, I’ve been asked countless times, “Aren’t diamonds just a commodity?  How could two diamonds with the same shape, size, cut, color, and clarity not cost the same? Shouldn’t I just buy the less expensive diamond, since it’s a better deal?”  

These are fair questions, and the less expensive diamond could be a great decision, but it could also be a very big mistake. It could be that both diamonds are truly identical, on paper and in reality. In this case, of course, the less expensive diamond is the better choice. But keep in mind that two diamonds may be identical on paper but still have very different characteristics and desirability. Unless you and your jeweler know how to spot the differences between two diamonds that appear to be the same on paper, you could be led into a costly mistake. That is where the expertise and honesty of your jeweler come into play. 

So how can two diamonds that appear to be the same on paper be different in reality?

Different Gemological Laboratories

First, not all gemological laboratories grade diamonds with the same strictness. They may be using the same methods, and they may, theoretically, be using the same criteria, but their application of those criteria and their discretionary judgments are different. The GIA is reputed to be the strictest grading laboratory, but even its graders don’t always get it right.

Different Gemologists

Second, even within the same laboratory, two gemologists may make different judgments about the same diamond. As a result, two diamonds of different qualities can get the same grade. If a weaker diamond gets the same grade as the stronger diamond, and if the seller prices the diamond based on what it really is rather than just the written grade, the weaker diamond will cost less (as it should), but will appear to be a great deal compared to the more expensive diamond. Of course, in reality, they are not the same quality, and each may be properly priced, in comparison to the other.

Mistakes in Grading

Third, the gemologist may simply make a mistake in grading a diamond. A seller of a diamond with such an inflated grade is not going to ask the laboratory to correct it. He may sell it for a relatively low price (giving the impression of a great deal), but in reality, the diamond is less desirable (and, truthfully, less valuable) than a properly graded diamond.

Judgments of Value

Finally, and perhaps most important, gemological graders do not necessarily understand that when you purchase a diamond, you want one that is pretty.  This is more than just a matter of grade; it is a question of value. It is a question of understanding what makes a diamond desirable. Gemological laboratories and their gemologists do not purchase diamonds. They don’t put their money on the line. They don’t evaluate more than the strict “Four C’s” of a diamond. Accordingly, their certificates do not tell you whether the subject diamond is one you should purchase or stay away from.

We, who put our money on the line and buy diamonds, have to understand what makes a diamond desirable to the end user and why, between two diamonds of the same grade, one may be worth purchasing and the other not.  We have to decide for ourselves whether the certificate reflects the true color of the diamond or whether it is it influenced by other factors. We need to determine whether the clarity grade is accurate and whether the inclusion is desirable or not. 

A Perfect Example

As an example, I was recently working with a customer who was interested in a 0.81ct round diamond of ours, with a GIA certificate graded H color, VS2 clarity. At the same time, she was considering a 0.80ct GIA certificated H VS2 diamond from another source who had borrowed the diamond from its owner to try to sell it to her. She showed me a copy of the certificate of the diamond she was being offered and I told her that it looked like a very good diamond on paper but that I couldn’t be sure without seeing the diamond. After telling me that she wanted to purchase her diamond from us, she asked me if I could obtain the other diamond and compare the two diamonds. I was able to obtain the diamond from the owner.

The comparison was truly enlightening, but also frightening at the same time. The other diamond did have a great certificate and paper grade.  However, in looking at the diamond itself, I could clearly see that it was undesirable. It had a brown cast to it with a steely darkness. Compared to my H color, this other diamond was dark and lifeless.  Holding the stones side by side, my customer was able to see the difference immediately.  I told her, in no uncertain terms, “you don’t have to purchase my diamond, but you definitely shouldn’t purchase this other one.” I also told her than any seller who would sell her the other diamond was doing her a great disservice. My diamond was desirable, the other was not. But you could only see that from the diamonds themselves, not from their certificates.

What is the Lesson?

What is the lesson here? You have to purchase your diamond from a source that truly understands diamonds and invests his own money in his inventory. When one spends his own money on something which he has to sell, he’s careful to look beyond the paper and examine the goods. That is the only way that people in my business can give our customers true value for their money.