Semi-Precious Gemstones: Lapis Lazuli & Lazurite
Lapis Gems used in Jewelry
Source: Afghanistan, Egypt, Canada, Chile, Myanmar, Russia, South America, USA
Lapis Lazuli, or lazurite is an opaque semiprecious stone that is characterized by its deep violet-blue color. Lapis was the source for a vivid blue pigment known as "azzurrum ultramarine," or "genuine ultramarine" which was used in fine-art oil paints until its synthesis (synthetic ultramarine or French ultramarine) in the 1928.
Lapis was treasured by the ancient Egyptian and Babylonian civilizations, and was often worn by royalty (blue being the color of royalty in many ancient cultures), and the funerary mask of the young Egyptian king Tutankhamun was heavily decorated with inlayed Lapis Lazuli. Powdered lapis was also used as a pigment in paint, cosmetic eye shadow, and in medicines. Lapis was also a popular gemstone with the ancient Chinese, Greeks, and Romans.
The first part of this gem's name "lapis" is Latin for "stone." The word "lazuli" is the genitive form of the medieval Latin word lazulum, which came from the Persian word lazhuward, meaning "azure" or "blue." Taken as a whole, lapis lazuli literally means "stone of azure" or "blue stone." Lapis is sometimes flecked with metallic inclusions, imparting a quality that was said to be like "the serene blue heavens fretted with fire" [5].
Lapis lazuli is not a single mineral, but a complex aggregate rock that is colored by lazurite, and containing hauynite, noselite, and various other minerals. Lazurite is a feldspathoid silicate mineral composed of sodium, aluminium, silicon, oxygen, sulfur, and chloride. Lapis Lazuli is often flecked with golden pyrite, sodalite, and/or calcite inclusions. Lapis lazuli commonly forms as veins or layers in crystalline limestone, as a byproduct of contact, or thermal metamorphism. Associated minerals are apatite, feldspar, and zircon.
Lapis lazuli Chemistry, Physical Properties
Lapis lazuli Optical Properties
Due to its porous and opaque nature, lapis is typically cut and shaped into a cabochon, strung as rough, unpolished nugget-like beads, or used as an inlay material.
Lapis Mining in Sar-e-Sang
Mines at Sar-e-Sang (Sare Sang) located in the Kokcha Valley of Badakhshan Province (Badakshan; Badahsan), Afghanistan are the principal source for higher-quality lapis lazuli (aka: Persian lapis, Afghan lapis) lazurite today. Secondary sources are in the Lake Baikal region of Siberia, Russia (Siberian lapis) and Ocalle, Chile (Chilean lapis). Chilean lapis is composed of blue lazurite, as well as calcite, diopside, haŸyne, pyrite and wollastonite.
Reconstituted or Dyed Lapis Lazuli
Paler, greenish varieties of Chilean lapis are often dyed or acid-washed to obtain a deeper blue color. Dying is accomplished using ferric ferrocyanide (Prussian blue) or other pigments. Selective dying may take place to cover up small white flecks of calcite. Dying can sometimes be detected by swabbing the stone with a Q-tip soaked in acetone or nail-polish remover. Reconstituted lapis is made up of natural stone, or stone fragments that have been pulverized into a powder, soaked in binding agents, then pressed into a solid mass to be re-cut.
Imitation Lapis Lazuli
A lapis imitation known as "Swiss Lapis," or German Lapis" is created from dying paler varieties of chalcedony, ironstone or quartz jasper with ferrocyanide. A Chelsea Filter can be used to distinguish genuine lapis from Swiss lapis which will appear as red.
Lapis lazuli was successfully simulated by Pierre Gilson Sr. of France in the 1970s but the synthetic version is slightly softer than natural lapis. The Gilson version contains flecks of pyrite flakes to imitate the look of natural Afghan lapis, but does not contain the characteristic calcite or sodalite inclusions. Sintered synthetic blue spinel was also used in the past as a lapis simulant.
Bibliography and Reference on Lapis Lazuli
1. Robert R. Coenraads, Lapis Lazuli from Coquimbo, Chile  . www.gia.metapress.com
2. Paul R. Shaffer, Rocks, Gems and Minerals . Martin's Press
3. Renee Newman, Gemstone Buying Guide . International Jewelry Publications; 2nd edition
4. Antoinette L . Matlins, Antonio C. Bonanno, Gem Identification Made Easy . Gemstone Press
5. F. Rogers, A. Beard, 5000 Years of Gems & Jewelry. FA Stokes Co., N.Y.
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