Lapis lazuli is a deep blue semi-precious stone that has been prized for its intense color and natural beauty for over 6,000 years. But what exactly gives lapis lazuli its distinctive blue hue? The answer lies in its chemical composition and crystalline structure.
Chemical Composition
Lapis lazuli consists primarily of the minerals lazurite, calcite, and pyrite.
Lazurite is responsible for the vibrant blue color of lapis. It contains sulfur ions that, when combined with silicon, oxygen, and aluminum, create the deep ultramarine blue that lapis is so famous for. The chemical formula for lazurite is:
(Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2
Calcite makes up the white portions in lapis lazuli. It adds luminosity and contrast to the blue lazurite. Calcite is a form of calcium carbonate with the chemical formula CaCO3.
Pyrite adds flecks and streaks of metallic gold within lapis stones. The chemical formula for pyrite is FeS2.
So in summary, it is the sulfur ions in lazurite that give lapis lazuli its saturated royal blue color when combined with other minerals like calcite and pyrite.
Crystalline Structure
In addition to its chemical composition, the crystalline structure of lapis lazuli contributes to its blue color.
Lapis has a triclinic crystalline structure, meaning its crystal lattice is arranged in an asymmetrical pattern. This allows certain wavelengths of light to be absorbed while others are reflected back to the eye.
The specific wavelengths associated with blue light in the visible color spectrum have an energetic resonance with the electrons within the sulfur ions in the lazurite crystals. This causes the blue wavelengths to be reflected back more than other colors, creating the characteristic blue appearance.
Meanwhile, the crystalline shapes cause white light to scatter within the stone, creating a sense of depth and dimensionality. So the interplay between the unique chemical bonds in lazurite and the orderly molecular structure of the crystals produces the saturated royal blue with flecks of white and gold that makes lapis lazuli so prized.
Source Locations
The best quality lapis lazuli has traditionally come from mines in Afghanistan, Chile, Russia and Pakistan.
| Country | Notable Lapis Mining Locations |
|---|---|
| Afghanistan | Badakhshan province |
| Chile | Andes Mountains |
| Russia | Lake Baikal |
| Pakistan | Gilgit-Baltistan |
Afghanistan, in particular, has produced lapis lazuli for thousands of years from the Sar-e-Sang mines in the Badakhshan province. The vibrant blue color and crystalline flecks found in Afghan lapis are unmatched.
History and Significance
Lapis lazuli has been mined and traded as a gemstone since the earliest civilizations due to its rare beauty and the difficulty of accessing the remote locations where it is found.
Some key facts about the history of lapis lazuli:
– Earliest lapis lazuli jewelry has been found in the Mehrgarh culture in Balochistan dating back to around 5000 BC
– Lapis was highly valued in Ancient Egypt, where it was obtained from trade routes to Afghanistan and used in jewelry, carvings, and protective amulets
– Ultramarine, the original natural blue pigment used in medieval painting, was made from finely ground lapis lazuli
– Mines in Afghanistan provided lapis to markets along the ancient Silk Road, spreading its trade as far as China
– Lapis jewelry has been found dating back to the Renaissance, where its blue was associated with royalty and power
So for millennia, the brilliant blue of lapis lazuli has been associated with prestige, wisdom, and honor due to its beauty and scarcity.
Uses in Jewelry
The most common use of lapis lazuli today is in jewelry, where it is frequently carved into cabochons, beads, and inlay designs. The unique color makes it a popular choice for:
– Rings – its durability makes lapis ideal for daily wear rings and statement pieces
– Pendants – allows the stone to be displayed in a focal point, enhanced by metallic settings
– Earrings and necklaces – strands of lapis beads or accents have a striking color impact
– Cufflinks and tie clips – provides a bold pop of color and texture against formal attire
– Watch faces – lapis makes a beautiful natural alternative to enamel or paint
– Mosaics and inlay – thin sheets are ideal for geometric designs and floral motifs when combined with other materials
Lapis has a Mohs hardness of 5-6, making it durable enough for most jewelry as long as it is not subjected to hard blows that may fracture it. Its relative softness also makes lapis lazuli easy to carve, polish, and incorporate into designs. But care should be taken to avoid prolonged exposure to acids or harsh chemicals that could damage the surface.
Price and Value
Natural lapis lazuli ranges in price from $1 to $100+ per carat depending on quality. Some factors that determine the value of lapis include:
– Color – deep royal blue is most desirable. Pale or greenish blue reduces value.
– Clarity – minimal veining and inclusions increases value. Calcite presence adds interest without detracting value.
– Texture – visible pyrite flecks add depth. Smooth uniform texture is ideal.
– Cut – cabochons, rounds, and freeform shapes show color. Carving and calibration add artisan value.
– Size – rare to find clean stones above 10 carats. Premium paid for gemstone-grade material over 3 carats.
– Source – Afghan lapis is consistently top quality. Chilean and Russian also command high value.
While not as expensive as sapphires or rubies, natural untreated lapis lazuli is still relatively rare. Top quality lapis with vibrant blue color can command prices competitive with other natural gemstones.
Synthetics and Imitations
The surge in popularity of lapis lazuli has led to the proliferation of synthetic lapis, simulated lapis, and lapis lazuli doublets in the market. These imitation stones sell for a fraction of the cost of natural lapis, making it important to test suspect stones.
Some identification features to look for:
| Feature | Natural Lapis Lazuli | Synthetic/Simulated |
|---|---|---|
| Color | Royal blue with variations and flecks | Uniform blue or dyed color |
| Texture | Uneven with visible pyrite | Glittery, spotty, or uniform |
| Hardness | 5-6 on Mohs scale | Softer than natural |
| Natural markings | White calcite veins | Few or no veins |
| Price | $50 to $500 per carat | <$10 per carat |
Doublets made of a thin slice of lapis capped with glass or resin are sometimes used in lower-end jewelry. Genuine lapis will feel cool and heavy compared to plastic imitations. Buying from a reputable seller can help avoid misleading lapis-like alternatives.
Alternative Blue Gemstones
While lapis lazuli is unique in its vibrancy and flecked texture, there are other blue gemstones that offer similar bold hues. These can make attractive lower-cost options to complement or stand in for lapis:
– Sodalite – Rich royal to ultramarine blue with white veining. Softer than lapis.
– Blue lace agate – Pale to sky blue banded agate that takes a high polish. More delicate than lapis.
– Blue topaz – Sky blue enhanced by irradiation. Higher brilliance than lapis but less natural looking.
– Tanzanite – Ranges from blue to bluish-purple. Much rarer than lapis but with similar bold color.
– Iolite – Blue to bluish-purple pleochroism. Lower density than lapis but with excellent hardness.
– Dumortierite quartz – Dark dusty blue quartz. Does not have the pyrite flecks of lapis but has similar vibrancy.
For natural blue gemstones, azurite and turquoise are softer than lapis lazuli. But they can provide striking blue-green hues when properly set in jewelry.
Conclusion
From the remote Badakhshan mines in Afghanistan to the pigments used by Renaissance masters, lapis lazuli has captivated people for over 6,000 years with its deep blue flecked majesty. Its rare, natural color is derived from the combination of lazurite, calcite, and pyrite crystals. This beautiful and durable material continues to be highly valued in jewelry and carvings today. Yet nothing compares to the vibrant blue of natural, untreated lapis lazuli from the most fabled sources in the East. With its mix of history, mysticism, and breathtaking color, lapis is likely to remain one of the world’s most cherished blue gemstones.
