An air dust blower — commonly known in photographic and optical supply circles as a rocket blower — is a hand-held tool comprising a compressible rubber or silicone bulb attached to a tapered nozzle. When squeezed, the bulb expels a controlled jet of air sufficient to dislodge loose dust, fibre, and fine debris from gemstone surfaces, facet junctions, and the optical elements of gemmological instruments, all without any physical contact with the specimen. It is a standard item on every well-equipped gemmological bench.

Function and Importance

Even a single dust particle resting on a facet can introduce a spurious inclusion-like feature under magnification, or scatter light in a manner that distorts colour assessment and photography. Before any examination under a loupe, binocular microscope, or spectroscope, and before documentary photography, a brief application of the blower ensures that what the gemmologist observes is intrinsic to the stone rather than an artefact of surface contamination. This discipline is particularly important when assessing clarity grades, mapping inclusions, or capturing images intended for laboratory reports.

Preference Over Compressed-Air Canisters

Aerosol compressed-air canisters, while superficially similar in purpose, carry a meaningful drawback: the propellant gases used — typically difluoroethane or tetrafluoroethane — can deposit a fine chemical residue on gemstone surfaces and optical coatings, especially if the canister is tilted or nearly empty and liquid propellant is expelled. This residue may temporarily alter surface lustre and can complicate subsequent cleaning. The manual rubber bulb blower produces only ambient air, leaving no chemical trace, and is therefore the preferred tool for delicate optical work and gemstone examination.

Use on the Gemmological Bench

Beyond gemstones themselves, the air blower serves several bench functions:

• Clearing dust from the stage and objectives of a binocular gemological microscope before a session.
• Removing debris from refractometer contact liquids or the hemicylinder surface prior to refractive index readings.
• Cleaning spectroscope slits and fibre-optic light guide ends.
• Preparing stones for close-up photography, where even a single fibre can ruin an otherwise technically sound image.

Proper technique involves holding the stone or instrument at a slight angle so that dislodged particles fall away rather than being redistributed across the surface. Several short, directed bursts are generally more effective than a single prolonged squeeze.

Selection and Care

Quality blowers are constructed from anti-static silicone or natural rubber to prevent the bulb itself from attracting and re-depositing dust. A one-way valve in the nozzle, present on better-made examples, prevents the blower from drawing contaminated air back through the nozzle tip on the intake stroke. The tool requires no maintenance beyond occasional inspection to ensure the nozzle tip is clean and the bulb retains its elasticity.