Lapis Lazuli is a deep blue stone prized since antiquity, notably used as the valuable ultramarine pigment during the Renaissance. Its enduring popularity has created a market for fakes and enhanced versions. Understanding the difference between a natural specimen, a treated stone, and an imitation is necessary to ensure a genuine purchase. The stone’s complex composition provides unique visual characteristics that serve as primary indicators of authenticity.
Defining Genuine Lapis Lazuli
Lapis Lazuli is classified as a metamorphic rock, a naturally occurring combination of several minerals fused under intense heat and pressure. Its intense blue color is primarily due to lazurite, a blue silicate mineral that typically makes up 25% to 40% of the rock. Genuine Lapis Lazuli also characteristically contains white calcite and metallic pyrite. The calcite appears as white streaks, while the pyrite forms glistening, gold flecks, giving the stone a “starry night” appearance. High-quality Lapis is defined by a deep blue color with minimal white mottling and an uneven distribution of pyrite inclusions.
Common Treatments and Enhancements
Many Lapis Lazuli specimens have undergone treatments to improve their appearance or durability. The most common enhancement is dyeing, used to deepen or standardize the blue color of lower-grade material. Dyes are often applied to mask the white streaks of calcite, making the stone appear more uniform.
Another frequent treatment is stabilization, which involves impregnating the stone with wax, oil, or transparent resin. This process improves surface luster and polish while increasing durability and protecting the color, especially if dye was used. Buyers should be aware that stabilized stones, while still Lapis Lazuli, have been permanently altered from their original condition.
Identifying Fakes and Simulants
The market contains two main categories of fraudulent material: natural stones dyed to look like Lapis Lazuli, and manufactured composites.
Natural Simulants
Common natural simulants include dyed Howlite or dyed Jasper, sometimes sold as “Swiss Lapis.” These stones are typically softer and lack the complex mineral structure of genuine Lapis, though they mimic the deep blue hue. Sodalite is another natural stone often mistaken for Lapis Lazuli, as it has a similar color but typically lacks the characteristic gold pyrite inclusions.
Manufactured Fakes
Manufactured simulants are materials created specifically to imitate the stone’s appearance. Reconstituted Lapis is made from crushed fragments of the stone or other minerals mixed with plastic or resin and pressed together. Synthetic Lapis, such as Gilson Lapis, is a lab-grown material that chemically mimics the stone’s composition but is often too uniform in color and inclusion placement.
Testing for Authenticity
The most reliable way to check authenticity involves close visual inspection of the pyrite. In genuine Lapis Lazuli, the flecks appear distinctly metallic and are scattered unevenly, often showing sharp, angular edges. Fake “pyrite” is often brass filings, gold-colored paint, or flat, rounded flakes that are too evenly spaced.
A simple way to test for unstable dye is to rub the stone with a cotton swab dipped in acetone in an inconspicuous area. If the swab picks up blue color, the stone is dyed, indicating a low-grade stone or a complete fake. Genuine Lapis Lazuli is also opaque and should feel noticeably cool to the touch, unlike plastic or glass simulants.