Gem Instruments Dichroscope (c.1960)
$0.00
Skip to product information
Gem Instruments Dichroscope (c.1960)
$0.00
The design of this 1960 model exemplifies the shift toward robust, handheld scientific instruments that preceded the formal creation of GIA’s standalone division, Gem Instruments Corporation (established in 1966). The device features a dense, cylindrical main barrel coated in a protective black matte finish, paired with contrasting silver-toned metallic caps on both ends. Internally, the unit relies on a classical optical configuration consisting of an aperture, a high-clarity Iceland spar (calcite) rhomboid prism, and a focusing eyepiece lens. By splitting a transmitted beam of light into two separate rays polarized at right angles to one another, the construction allows the gemologist to view the two distinct pleochroic colors of a doubly refractive gemstone side-by-side, easily distinguishing it from singly refractive glass imitations or color-banded alternatives.
This mid-century optical instrument is a classic representation of early specialized gemological equipment distributed by the Gemological Institute of America (GIA). The principle of the calcite dichroscope was first introduced in the 19th century by Austrian mineralogist Wilhelm Karl von Haidinger, who invented the initial configuration to analyze pleochroism in crystals. Recognizing the commercial need for accessible, rugged field tools for jewelers, GIA began manufacturing and adapting its own proprietary testing equipment starting in the late 1930s under the guidance of early directors and pioneering innovators like Robert Shipley Jr. By the year 1960, this pocket-sized unit had become a standard staple within the student instrument kits provided to aspiring Graduate Gemologists.
During the early 1960s, a standalone pocket dichroscope of this configuration was sold through the institute's specialized tools catalogs for a modest price of approximately $12.00 to $18.00 USD, serving as an affordable yet essential investment for jewelry appraisers. At the time this specific unit was manufactured and distributed, the international headquarters of the Gemological Institute of America was operating out of its longtime campus located at 11940 San Vicente Boulevard, Los Angeles 49, California, U.S.A.—decades before the organization consolidated its global research, testing laboratories, and educational branches to its current world headquarters in Carlsbad, California.