Gem of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment


April, 2006

Lapis Lazuli

Lapis Lazuli is not, like most gemstones, a pure mineral, but rather a rock composed of varying proportions of the minerals: lazurite, sodalite, hauyne, calcite, and pyrite. Primarily the result of contact metamorphism of certain limestones, it is found in rather large deposits, but at few locations. The primary historical mining site was in Northern Afghanistan, and remains so to this day. Secondary deposits in Siberia, Canada, and Chile supplement the supply, but with generally lower grade material.

[High grade Afghani lapis rough]

Used since ancient times, (some estimates say as early as 6000 BCE), it is still a popular choice today. Beads, jewelry, and carvings have been found in numerous archeological sites from that time onward, indicating a spread in use from Afghanistan, throughout the Middle East and Egypt, to Asia, and the Roman World.

[Babylonian lapis "melon" bead circa 3000 BCE]

The name "lapis lazuli" comes from the Persian "lazhward", and literally means "blue stone". Throughout the Latin speaking Roman World, however, the word "sapphirus" was used (with the same meaning), and has lead to speculation that in certain historical sources, the "sapphires" of antiquity were really lapis. The Egyptians long valued this stone, not only as a source of carving and inlay material, but also in ground form as a cosmetic. If you've ever wondered who to blame for bright blue eyeshadow....

Painters from pre-Renaissance times until the Modern Era used ground lapis as their pigment "ultramarine", and that old formula is still used today by museum conservators (and forgers!).

Jewelry uses predominate today, though, and most commonly this gem is set in silver in modestly priced jewelry pieces. There is a growing trend, however, to emulate the jewelers of earlier times, and to set fine quality stones in gold, with diamonds or colored gems.

[Contemporary lapis, malachite and gold jewelry piece by Alex Horst, classic Greek key motif in a gold and lapis ring, contemporary silver, lapis and chrysoprase piece]

Lapis has always been a gem of choice for inlays, insets and intarsias. How could any gem artist resist the contrast and eye appeal of its bright blue color?

[Multi-gem intarsia with lapis border and frame, earrings featuring lapis and other gems inset into silver channels, lapis and tiger'seye inlay piece]

Lapis carvings are still a popular item, and beads can be baroque or round.

[Carved lapis earring jackets, tumbled lapis chip bead strand]

The colors of lapis range from a medium greyish blue, to intense royal blue, to deep indigo, with varying amounts of white and brassy gold from calcite and pyrite, respectively. Some purists desire a gem that is almost entirely lazurite, in a deep uniform blue, but most seek a piece with a moderate to generous sprinkling of golden pyrite. Pliny the Elder in his famed ancient treatise on all things Natural, called lapis "a fragment of the starry firmament" in admiration of the deep blue with twinkling bits of gold.

[High grade lapis gems with varying amounts of pyrite suited to different tastes]

Although they don't agree as to how much pyrite is ideal, most all admirers and collectors of fine lapis, agree that, the less calcite, the better. White calcite can be seen as streaks or patches within the darker blue, or can predominate in the mix giving the rock an overall lighter blue shade. The popularity of denim/country-western clothing has given marketers a niche for what once was considered low quality, virtually unsalable material from Chile. Cleverly dubbed "denim lapis" it is sold widely on home shopping channels, at swapmeets, and through direct mail catalogues.

[Lapis pair with localized calcite areas, "denim" lapis pin, "denim" lapis cabochon with large amounts of calcite]

Perhaps it is this gem's long history, or its ethereal color scheme that make such it a highly significant stone amongst those who ascribe mystical, spiritual or healing properties to gemstones. It is an alternate birthstone for September in the European/American system, and has prominent positions in other systems as well.

Synthetics and Simulants

Lapis lazuli has been successfully synthesized by Gilson in France, and Chatham in the USA, and many of the large jewelry supply houses offer the synthetic version either with, or without, pyrite. Although the synthetics are a modern invention, lapis simulants go back at least as far as early Egyptian times. Artifacts using glass backed with blue paint, and blue ceramic materials in lieu of lapis, include the famed King Tut Death Mask. Such items attest to the Ancients love of this dark blue gem, and the ingenuity they used to simulate it when the natural material was scarce or too costly.

Modern era simulants include enamel, glass, plastic, and a variety of dyed gems such as howlite, and jasper (aka"Swiss lapis"). The only natural gemstone readily available in large enough sizes, and in a deep enough blue to be a convincing lapis simulant is sodalite.

[Synthetic, Gilson-type lapis cabochon, dyed howlite lapis simulant: Image courtesy of www.earthstones.com, sodalite, a natural lapis simulant]

Care

Although this gem's hardness of 5-6 suggests that some degree of care is needed in setting and wearing, it is still widely used in rings and bracelets --> it would be wise to choose a protective setting for these uses, or limit wear to less than 24/7. Even given protective care, a well worn ring or bracelet gem may need repolishing periodically. Pendants, earrings, brooches and tie or lapel pins can be worn daily with little worry. Steam, chemical solvents, and ultrasonics should be avoided for cleaning. The old standby of a soft brush and mild soap would be safest.


Value

Value in lapis is determined almost exclusively by color, with deep, intense, blue with violet tones being at the apex. Fine grained, uniform specimens attain a smooth highly polished surface not seen in lower grades. Calcite inclusions always lower the value, but pyrite inclusions enhance it in the minds of many collectors and jewelry lovers. The quality of polish, and the artistry of fashioning are also factors in value.


Gemological Data:

Makeup: rock containing a variable mixture of lazurite and other minerals

Luster: vitreous to greasy

Hardness: 5-6 depending on composition

Crystal structure: various

Cleavage: none

Density: 2.8

RI: 1.50 (mean)

Birefringence: none

Dispersion: none


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Go to: Homepage -- what's new in faceted gems -- what's new in designer cabochons and gem carvings -- gem of the month -- gem of the month archive -- birthstone of the month -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- about the ACS cutters -- settings for these gems --faceting information -- purchase UltraTec equipment