Micro-World Gems & Gemology, Summer 2022, Vol. 58, No. 2

Large Diamond Inclusion in Diamond

Diamond crystal inclusion exhibits triangular etch features.
Figure 1. Trigons seen on a diamond crystal inclusion visible through the crown of a round brilliant diamond. Photomicrograph by A’Dhi Lall; field of view 2.11 mm.

Recently, the authors examined a 2.01 ct Faint green round brilliant diamond with a fascinating diamond crystal inclusion that displayed a transparent, ghost-like appearance. Due to the large size of this nearly invisible crystal, the stone was given a clarity grade of SI2.

Cross-polarized light reveals strain between the host diamond and the diamond inclusion.
Figure 2. Strain between the host diamond and the diamond inclusion is revealed by the interference colors in cross-polarized light. Photomicrograph by A’Dhi Lall; field of view 13.55 mm.

Photomicrography was used to document the features of this inclusion. Triangular etch features, also known as trigons, were seen on the inclusion (figure 1). These are typically natural growth markings of diamonds, confirming the inclusion as diamond. The diamond crystal inclusion appeared to have sharp and easily recognizable faces. Images with cross-polarized light show strain between the inclusion and the host diamond (figure 2). A DiamondView image also reveals the diamond crystal inclusion (figure 3).

The diamond inclusion is clearly seen within the diamond host.
Figure 3. DiamondView image of the diamond inclusion in the diamond host. Image by Luthfia Syarbaini.

Generally, the beauty and value of a diamond increase with the absence of inclusions. Yet the presence of a diamond inclusion gave this diamond a certain distinction, which in the authors’ opinion added to its beauty and value.

Luthfia Syarbaini is a senior staff gemologist, A’Dhi Lall is a gemology associate, and Paul Johnson is manager of analytics, at GIA in New York.