Chalcedony is a cryptocrystalline variety of quartz that can come in a wide range of colors. While most common chalcedony colors like white, gray, blue, and brown are readily available, some shades and patterns are much rarer and more prized by collectors. Here's an overview of some of the rarest and most valuable color varieties of chalcedony.
Red
Red is one of the rarest natural colors for chalcedony. Most red chalcedony gets its color from trace amounts of iron oxide minerals. Good quality solid red stones are uncommon, with most showing pale pinkish-orange rather than a rich ruby red. Top quality blood-red chalcedony can be worth over $1000 per carat.
Blue
Natural blue chalcedony is also quite unusual. Most blue chalcedony is colored by trace copper minerals rather than iron. Stones are typically a pale sky blue or robin's egg blue rather than a deep sapphire blue. The most prized and expensive blue chalcedony is the rare intense sapphire-blue material from Oregon in the United States.
Green
Green is another rarely seen chalcedony color, with most green stones being low quality and unevenly colored. Rich green chalcedony colored by chromium is very uncommon, and fine emerald-green stones are highly valued by collectors. Green chalcedony is also sometimes formed by inclusions of chlorite minerals rather than color from trace elements.
Purple
True purple chalcedony is exceptionally rare, with very few localities producing stones with discernible purple hues. Most "purple" chalcedony is lighter lilac or lavender in color rather than a distinct purple. Manganese is most often responsible for giving chalcedony a purple tint. Fine saturated purple chalcedony can command prices over $5000 per carat.
Orange
While orange chalcedony is more common than many other colors, clean vibrant orange specimens are still valued. Most orange chalcedony owes its color to iron oxides. Caramel-orange, pumpkin-orange and amber-orange stones are the most frequently seen shades. Neon orange is one of the rarest and most coveted varieties of orange chalcedony.
Black
Solid black chalcedony is uncommon. Most black chalcedony is actually very dark gray or brown rather than a true black. Black color comes from inclusions of black minerals like hornblende, magnetite, or hematite. Jet black chalcedony is especially prized in carving and jewelry.
The most valuable and sought-after chalcedony combines multiple colors in bands, swirls, spots, or other patterns. Multi-colored stones display a range of hues in a single specimen. So in summary, while not overly precious, the rarest chalcedony colors are the intense hues on both ends of the color spectrum like blood-red, deep blue, and jet black.
