Diamond Types – What does it mean for Consumers?

Diamond typing is important to researchers and laboratories, but largely irrelevant to consumers. Determinations of diamond type are made on the basis of differences at the atomic level. Diamond is composed almost entirely of carbon atoms aligned in a very specific crystal lattice, but other atoms such as nitrogen and boron are commonly trapped among the carbon atoms during formation. While other impurities can also be incorporated, the diamond type classification system divides diamond into categories based solely on the presence or absence of certain nitrogen and boron impurities and the ways in which they are structured. Which one is present and how it is arranged in the carbon lattice determines the diamond type. The primary benefit to gemologists in understanding a diamond’s type is in being able to distinguish natural from synthetic and treated diamonds.

The most common is type I, consisting of type Ia and type Ib. Type I diamonds contain Nitrogen impurities, either in aggregates (Type Ia) or in isolated atoms (Type Ib). While different types are associated with different fancy colors, the vast majority of consumers will be considering diamonds in the normal range “D-Z”, and 95% of those diamonds will be type Ia. Some of the rare type Ib diamonds will have a vivid yellow color, sometimes referred to as ‘canary’. Nitrogen centers are also associated with fluorescence.

Type Ia are further broken down on the basis of how the nitrogen aggregates are configured within the carbon lattice. When the nitrogen atoms are separated in pairs, they are designated type IaA. When they surround a vacancy (a missing carbon atom), they are type IaB.

Type II diamonds are those with a non-detectable amounts of nitrogen. Type IIa diamonds have negligible impurities of any kind, while Type IIb are those with atoms of the element Boron trapped in the carbon lattice. Type IIb diamonds are associated with fancy blue diamonds.

Consumers sometimes express interest in colorless type II diamonds, believing that those diamonds are more pure and must therefore be of better quality. From a theoretical perspective that may be true, but there is no practical benefit. The impurities can only be detected with sophisticated scientific instruments such as the infrared spectroscope. While distinctions between types are important in detecting synthetic and treated diamonds, they hold no real-world relevance for consumers.

For a diamond shopper the operative factors are the 4C’s and the overall beauty of the stone within a given budget. The resulting color, whatever the type, and the cut craftsmanship and light performance of the diamond, are the relevant considerations for the consumer. It is of course important to know that the diamond has been through laboratory evaluation where advanced tests are conducted to determine whether the diamond is natural or synthetic, and whether it has been treated in any way.