Kunzite is the pink to violet, manganese-coloured gem variety of spodumene, a lithium aluminium chain silicate of the pyroxene group. It was first identified as a distinct gem variety in 1902, when material from the Pala district of San Diego County, California, was sent to George Frederick Kunz for examination. Charles Baskerville named the new variety in Kunz's honour later that year. Kunzite is the second of the three principal gem varieties of spodumene, alongside hiddenite (chromium-bearing green) and yellow-green ordinary spodumene.

Chemistry and properties

Spodumene has the formula LiAlSi₂O₆ and crystallises in the monoclinic system. In kunzite, the colour-causing chromophore is manganese in the trivalent state (Mn³⁺), which produces a strong absorption in the green-yellow region of the visible spectrum and a transmission window in the pink-to-violet range. Refractive indices are 1.66 to 1.68, with a birefringence of 0.014 to 0.027. Specific gravity ranges from 3.16 to 3.20. Hardness is 6.5 to 7 on the Mohs scale, with two perfect cleavages along {110} that meet at approximately 87 degrees and produce notoriously brittle cleavage planes.

Pleochroism in kunzite is pronounced and presents a major cutting consideration. Three distinct colours are visible along the principal optical directions: a strong pink to violet along the c-axis, a paler pink along the b-axis, and a near-colourless to faint pink along the a-axis. The cutter must orient the table perpendicular to the c-axis to capture the deepest colour, which means rough must be examined and oriented before any cutting begins.

Colour stability

Kunzite is photosensitive. Prolonged exposure to direct sunlight or to ultraviolet radiation can fade the pink colour, and some of the trade still refers informally to evening stones for kunzite that is best worn under artificial light. The fading is gradual and varies with the source of the material; California stones are generally regarded as more stable than Brazilian or Afghan production, although the data are not uniform. Heat treatment and gamma irradiation are sometimes used to deepen pale material to richer pink-violet, but treated colour can be unstable on its own and may fade in light. Reputable laboratories distinguish treated from untreated material on request.

Sources

The principal historical source remains the Pala-Mesa Grande district of San Diego County, California, where lithium pegmatites in the Stewart Lithia, Pala Chief, White Queen, Tourmaline Queen, and Himalaya mines have produced gem kunzite continuously since the early twentieth century. The Brazilian states of Minas Gerais (especially around Itinga and Conselheiro Pena) are major modern producers. Afghanistan's Kunar and Nuristan provinces yield very large gem rough, with some pieces in the multi-hundred-carat range. Pakistan's Chitral and Bajaur districts produce material continuous with the Afghan output. Madagascar, Mozambique, and Nigeria contribute smaller quantities.

Inclusions and identification

Kunzite typically shows minor inclusions: tubular hollows along the c-axis, two-phase fluid inclusions, and partial healing fractures. Specimens are often very clean by gem standards, partly because included or fractured rough is cheap to discard relative to the volume of clean material available. Identification on a refractometer and polariscope is straightforward; the manganese-related absorption spectrum is diagnostic.

Cutting and setting

The combination of pleochroism, perfect cleavage, and brittle response to bench shock makes kunzite a difficult stone to set. Cutters traditionally produce large faceted stones (50 to 200 carats and beyond), often emerald or rectangular cushion cuts that exploit the long pegmatite rough and place the table perpendicular to the c-axis. Setters should avoid bezels with sharp pressure points, hot torch repairs, ultrasonic cleaning, and any impact across cleavage planes. The stone is best suited to occasional-wear pieces (cocktail rings, pendants, earrings) rather than daily-wear engagement rings.

Trade considerations

Kunzite has remained a relatively affordable large-stone gem because of the abundance of clean rough and the relative absence of historical demand. Pricing follows colour saturation, size, and clarity, with deep pink-violet stones over 30 carats commanding the strongest premiums. The Afghan supply of very large stones occasionally produces pieces over 1,000 carats; these have been cut for collectors, museum acquisitions, and a small number of major estate jewellery commissions.

The naming honour reflects the broader career of George Frederick Kunz at Tiffany & Co., who recognised the material and arranged its commercial introduction in the years immediately following 1902.