GIA Duplex II Refractometer (White Edition c. 1996)

The white-edition GIA Duplex II refractometer, released in January 1996, represents the continued evolution of GIA’s most widely adopted optical testing instrument. Functionally identical to the earlier gray model introduced in 1979, this updated version retained all core engineering principles that made the Duplex II a standard in gemological laboratories and classrooms worldwide.

Like its predecessor, the 1996 white Duplex II features an oversized optical prism designed to fully support the spot method, enabling accurate refractive-index readings on cabochons and other gems with curved surfaces. Its integrated polarizing filter remained a defining feature, allowing users to observe optical behavior and determine the gemstone’s potential crystal system, greatly expanding the instrument’s diagnostic capabilities.

The shift to a clean white exterior was primarily aesthetic, aligning with GIA’s mid-1990s redesign themes while preserving the lightweight, durable plastic housing introduced in the gray version. This construction reduced weight and production cost compared with the metal-bodied Duplex I, while maintaining the precision optics and stable illumination required for dependable RI measurements.

The 1996 white Duplex II stands as the final major iteration of the model, symbolizing GIA’s ongoing commitment to accessible, accurate, and professionally standardized gemstone testing instruments.