Lapis lazuli is an aggregate of several minerals. It contains three minerals in varying amounts: lazurite, calcite, and pyrite. Sometimes, it also contains one or more of the following: diopside, amphibole, feldspar, and mica.
Lazurite grains provide its characteristic blue color, while calcite shows up as white flecks or streaks . Pyrite provides golden, metallic-looking spots.
Many people associate lapis with dark blue, but it’s also found in other shades of blue. Its most desirable colors are slightly greenish blue to violetish blue, medium to dark in tone, and highly saturated.
Lapis is also found in other shades of blue, and even other hues. Its color 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 color in lapis. For example, lazurite is responsible for producing royal blue lapis, while a mineral called afghanite creates a pale blue shade.
Lapis value is based on color 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. 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 color. Typically, lapis cutting styles for use in jewelry are cabochons, beads, inlays, and tablets. Lapis lazuli’s use has never been limited to jewelry alone. It’s also a popular carving material.
Throughout its history, lapis has been fashioned into practical objects, including game boards, bowls, dagger handles, hair combs, and amulets.Today, lapis is frequently fashioned into freeform and nature-themed sculptures. Some of these carvings become wearable art, others are purely decorative.
Lapis treatments are common, but treated lapis is not very stable, and it’s always less valuable than natural lapis. Lapis might be dyed, impregnated with wax or plastic, or heated and then dyed. The dye can come off if it’s rubbed with acetone (nail polish remover) or denatured alcohol, so sometimes it’s sealed with wax or plastic. However, wax sealers can deteriorate when they’re exposed to heat or solvents.
Lapis that hasn’t been dyed might be impregnated with wax or with oil to improve color and luster. These treatments have only fair stability, and a gemologist can detect them.
Lapis is mined in several areas. The traditional source of the finest lapis lazuli is the same today as it was thousands of years ago which is the mountains of Afghanistan. The lapis lazuli mines are located in the Kokcha valley, a deep canyon only about 200 yards wide. The Afghani mines are huge caverns connected by narrow, hot, stuffy passageways. Miners use dynamite to rattle the rough lapis loose from the cave walls. Miners backpack blocks of lapis rough down steep mountain trails to campsites, a treacherous journey that takes about a week and a half. The bulk of the rough then goes to western Pakistan for fashioning.
Other major sources of lapis Lazuli are Chile and Lake Baikal in Siberia, Russia.