2026

An uncommon artificial resin feature in a brazilian Paraiba tourmaline

By Dr. Wei Zhou, first published in Facette 30 (March 2026)

Recently, we examined a vibrant Brazilian Paraiba tourmaline weighing approximately 6 carats (Figure 1). One particular internal feature stood out that we found interesting for sharing.

Figure 1: A Brazilian Paraiba tourmaline weighing approximately 6 carats. Photo: L. Phan, SSEF.
Figure 2: Comparison of the colour of the CVD diamond under daylight conditions, before and after exposure to deep-UV light. Photo: SSEF.

As seen in Figure 2, an elongated, geometric negative inclusion in this Paraiba tourmaline—surrounded by a hill-like structure—caught the attention of our experienced gemmologists. At first glance, our gemmologists thought it might be a natural internal growth feature or a large healed fissure—nothing out of the ordinary. But when we looked closer using Raman spectroscopy, the results told a different story.

Surprisingly, the Raman result showed a clear spectral signature of artificial resin (Figure 3), indicating that the cavity had likely been filled during a clarity enhancement process. What made it especially interesting was the shape: instead of the usual round bubble we might expect, the sticky, viscous artificial resin had formed a sharp-edged, geometric shape—something rarely seen.

Figure 3: Raman results showed a clear spectral signature of artificial resin. Spectra: SSEF.
In gemmology, we are often reminded that the interplay between natural formation and human intervention can produce unexpected results. While bubbles are typically round, this geometric inclusion challenges conventional expectations—offering a fascinating example of how complex and intriguing gemstone interiors can be. The blend of nature growth and human enhancement sometimes creates internal ‘landscapes’ that are not only scientifically interesting but visually fascinating too.