Hand-Blown Convex Belgian Mirror Glass Diamond Cutting: The Thikri Glass Craft

At the center of authentic Thikri mirror inlay lies an unusual material: mouth-blown convex glass. In the 17th and 18th centuries, plate glass technology was in its infancy; large, flat glass mirrors were astronomical luxuries imported at vast expense from Venetian workshops on the island of Murano. To circumvent this limitation and achieve a vastly more dynamic optical effect, European glassmakers developed the craft of blowing hollow glass spheres measuring 200 to 400 millimeters in diameter.

While the hollow glass ball was still hot from the furnace, the glassblower injected a molten liquid amalgam of lead, tin, bismuth, and mercury through the blowpipe into the interior cavity. Rotating the sphere continuously coated the inner glass wall with a mirror-bright, silvery metallic film. Once cooled, these silvered globes were crated and shipped via maritime trade routes from Antwerp and Venice to Gujarat ports like Surat, before journeying by camel caravan to the desert capitals of Rajasthan. When broken, these spheres yielded hundreds of paper-thin, curving convex shards whose optical curvature transformed ordinary candlelight into brilliant celestial fireworks.

Cutting paper-thin, curved glass into intricate floral shapes is a delicate, nerve-testing lapidary craft. The master artisan (ustad) relies on an austere toolkit refined over centuries. The primary instrument is the heera kalam (diamond pen)—a forged steel rod fitted with a tiny industrial diamond crystal mounted at its tip in a copper or brass collet. Unlike modern carbide wheels that require flat rolling contact, the pointed diamond crystal can trace sharp curves, serpentine S-scrolls, and acute angles across spherical glass surfaces without slipping.

To assist the diamond scribe, the artisan uses the chimti—a pair of heavy, hand-forged iron pliers with broad, flat, smooth-ground jaws. Once a score line has been cut across the glass face, the craftsman grips the waste margin with the chimti and applies a subtle downward shearing torque. With a crisp, sharp click, the glass fractures cleanly along the microscopic diamond fault line. Through thousands of precise, rhythmic plier nibbles, the artisan coaxes organic, living forms out of cold, brittle glass.

The visual grammar of Rajasthani Thikri is rooted in botanical naturalism stylized through Indo-Islamic geometry. Every individual composition is assembled from standardized modular glass shapes, each requiring a specific cutting technique. The most common motif is the pankhuri (lotus petal)—an elongated teardrop shape with a broad rounded base that tapers to an acute, needle-sharp point.

To create a blooming lotus rosette, the artisan must cut twelve to twenty-four identical petals, graduating in size from tight central buds to expansive outer petals. Because the glass possesses natural spherical curvature, the artisan must orient the grain of the curve along the longitudinal axis of the petal; this ensures that the finished petal appears to curve three-dimensionally off the wall like a real flower. Other standard forms include the patta (serrated leaf), the kalli (tight flower bud), the leher (undulating floral stem), and the bindi (the central stamen, often cut as a tiny convex button less than 4 millimeters wide).

The chief technical difficulty in Thikri glass cutting is preventing damage to the delicate metallic reflective layer on the back of the glass. The tin-mercury amalgam or silver coating is only a few microns thick and has relatively poor mechanical adhesion to the smooth glass substrate. If an artisan applies excessive pressure or grips the glass improperly with the chimti, the metal film will peel, chip, or flake away from the glass edge, leaving an unsightly transparent rim around the finished piece.

To prevent this defect, master craftsmen cut glass over a thick, oiled leather pad that cushions shockwaves and prevents the metal backing from scraping against hard worktables. Experienced artisans frequently seal the back of antique glass plates with a thin wash of natural dewaxed shellac or dammar varnish before cutting; this reinforces the metal film, locking it to the glass and allowing razor-sharp lines to be snipped without edge flaking. Completed pieces are wiped clean with soft silk rags and organized into felt-lined wooden compartmentalized trays, protected from dust and airborne moisture until final installation.