Lapis Lazuli Quality Factors
Variously described as indigo, royal, midnight or marine blue, lapis lazuli’s signature hue is a slightly greenish blue to violetish blue, medium to dark in tone, and highly saturated. In its most-prized form, lapis lazuli has no visible calcite, although it might contain gold-coloured pyrite flecks. If the flecks are small and sprinkled attractively throughout the gem, their presence doesn’t necessarily lower lapis lazuli’s value. The lowest-quality lapis looks dull and green, the result of an excess of pyrite. Lapis with white calcite streaks is less valuable.
Although many people associate lapis with dark blue, it’s also found in other blue shades, and even other hues. Its colour can range from deep violet blue and royal blue to light blue to turquoise blue to a greenish blue. The combination of different minerals in the aggregate determines the colour. For example, the presence of lazurite produces lapis lazuli’s prized royal blue colour, while a mineral called afghanite creates a pale blue shade.
Lapis trade grades are based on colour and the presence or absence of calcite or pyrite. Lapis types on the market today, in order of their value, are:
- Persian or Afghan - Intense, uniform, medium dark, slightly violetish blue. Contains little or no pyrite, and no calcite
- Russian or Siberian - Various tones and intensities of blue. Contains pyrite and might contain some calcite
- Chilean - Often tinged or spotted with green, with obvious calcite matrix
A gemstone’s appearance might be described using an adjective that refers to a country or region, but that doesn’t necessarily mean the gem is actually from that area. Thus, lapis with a lot of white calcite spots and many green patches might be sold as “Chilean,” but this doesn’t mean it’s really from Chile.
For thousands of years, lapis has been fashioned to show off its rich, dark colour. Typically, lapis cutting styles for use in jewellery are cabochons, beads, inlays, and tablets, as well as decorative carvings.
Today, lapis is frequently fashioned into freeform and nature-themed sculptures. Some of these carvings become wearable art, others are purely decorative.
Lapis frequently contains varying amounts of whitish calcite matrix—the host rock that surrounds the gem—or flecks or veins of glinting yellow pyrite, or both. The gem can also have a smoothly uniform bodycolour, free of visible pyrite and calcite.
Lapis rough can be very large, so large fashioned stones are more common than with many other gemstones. Larger sizes are also more likely to be carved into art objects, used in designer jewellery, or cut into calibrated sizes.