Grossular is a calcium-aluminum garnet species that occurs in a wide range of colors, including green (tsavorite), yellow, brown, orange (hessonite) and colorless. It has Mohs hardness around 7–7.5, good toughness and no cleavage, making it a durable gemstone when properly set. Different color varieties have distinct trade names and market positions.
Price History
Value Drivers
Carat weight's impact varies by variety. Hessonite and lower-grade brown or yellow grossular are easily available in modest sizes, while fine tsavorite and top hessonite above 3–5 carats are rare and command strong premiums. Exceptionally large, clean tsavorite gems are particularly valuable.
Color is the primary value driver. For tsavorite, vivid, medium to medium-dark pure green with high saturation is most prized, while for hessonite, rich honey to cinnamon-orange tones are preferred. Brownish, overly dark or weakly saturated colors generally trade at lower levels.
Expectations for clarity vary: tsavorite is typically marketed as eye-clean or close to it, and obvious inclusions significantly reduce value. Hessonite often exhibits characteristic 'heat wave' or roiled internal textures that are more tolerated but still weighed against color and brightness. Overall, cleaner stones are more desirable across grossular varieties.
Cut is important for maximizing brilliance and managing tone. Well-designed mixed cuts keep grossular garnets lively and bright, particularly in darker greens and oranges. Because of their good durability, grossular garnets can be cut into a wide range of shapes, including precision cuts for high-end pieces.
Market Dynamics
Grossular garnets occur in contact metamorphic rocks and skarns worldwide, with significant gem deposits in East Africa (notably Kenya and Tanzania for tsavorite), Sri Lanka and other regions. Lower-grade material is relatively plentiful, while high-quality tsavorite and fine hessonite are considerably more limited.
Demand is strong for tsavorite and continues to grow as it is promoted as a rival to emerald with fewer treatments. Hessonite and other grossular varieties enjoy steady, if less intense, demand in both mainstream and niche markets.
Recent Trends: steady demand from the broader jewelry market, with gradual growth in online and designer channels for well-cut, natural stones.
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Insights
Tsavorite, the vivid green variety of grossular, was named and promoted by Tiffany & Co. in the 1970s, helping establish it as a high-end colored stone.
Hessonite garnet, sometimes called 'cinnamon stone,' has long been used in traditional jewelry in Sri Lanka and India.
Because grossular is typically untreated, it appeals to buyers who value natural color and clarity without enhancement.
Grossular's relatively high refractive index gives well-cut stones appealing sparkle, especially in lighter yellow and green hues.
Mining and security conditions in parts of East Africa can influence the availability and pricing of fine tsavorite.
Collectors often seek out rare color combinations and locality-specific grossular garnets, including mint greens and unusual yellow-greens.
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