A calico buff — also known as a cotton buff — is a lapidary polishing wheel constructed from multiple layers of woven cotton cloth stitched together in concentric circles. The stitching compresses and consolidates the layers, producing a wheel that is firm enough to carry abrasive compounds effectively yet sufficiently flexible to conform, to a limited degree, to the contours of a stone's surface. Calico buffs are standard equipment in gem-cutting workshops and are used in conjunction with polishing compounds such as cerium oxide, tin oxide, or diamond paste.

Construction and Materials

The term calico refers to a plain-woven, unbleached or partially processed cotton fabric — a material chosen for its moderate density and consistent fibre structure. When multiple plies are stitched concentrically and mounted on a central arbor, the resulting wheel presents a working face that resists deformation under moderate pressure. The density of stitching governs the wheel's firmness: more closely spaced stitching yields a harder face suited to aggressive pre-polish work, while wider spacing produces a softer action appropriate to final polishing stages.

Wheel diameters in common lapidary use range from approximately 75 mm to 300 mm, with thickness varying according to the number of plies laminated. Smaller wheels are favoured for detail work on faceted stones; larger wheels suit cabochon polishing and flat-lapping operations.

Use in the Polishing Sequence

In the lapidary polishing sequence, the calico buff typically occupies the pre-polish or intermediate stage — after the final abrasive lap has removed grinding scratches but before a softer felt or leather buff brings the surface to its ultimate lustre. Applied with cerium oxide or tin oxide slurry, a calico buff will efficiently remove the shallow scratches left by fine-grit laps on oxide-polished materials such as quartz, feldspar, and many oxide and silicate gems. For harder materials, or where a high-gloss finish is required in fewer steps, diamond paste of 1 µm to 3 µm grit is commonly used on calico.

The wheel's relative firmness is an advantage when polishing faceted stones: it maintains flat facet geometry better than a yielding felt or chamois surface, reducing the risk of rounding facet edges — a defect known in the trade as cutting over. For cabochons, the slight give of the outer ply allows the compound to work across a domed surface without creating flat spots.

Polishing Compounds Used

• Cerium oxide — the most widely used compound on calico for silicate and oxide gems; effective on quartz, chalcedony, topaz, and glass.
• Tin oxide — produces a high lustre on softer materials including calcite-group stones and some phosphates; also used on metal surfaces.
• Diamond paste — employed for harder gems (corundum, spinel, chrysoberyl) and where rapid stock removal with fine finish is required simultaneously.
• Aluminium oxide (alumina) — occasionally used as an intermediate compound before finer oxides.

Place in Lapidary Literature

John Sinkankas, whose technical writings remain a foundational reference for English-language lapidary practice, documents calico buffs as routine workshop equipment alongside felt, leather, and wooden laps. Their longevity in the craft reflects a practical balance of cost, availability, and performance: cotton cloth is inexpensive, the wheels are easily dressed with fresh compound, and worn surfaces can be trimmed back to expose a clean working face.

Care and Maintenance

Cross-contamination between compounds is the principal concern in buff maintenance. A wheel charged with coarser compound must not be used subsequently with a finer one, as residual abrasive will introduce scratches that defeat the purpose of the finer stage. Most workshops dedicate individual buffs to single compounds and mark them accordingly. Buffs should be stored away from dust and kept dry; cotton fibres absorb moisture readily, and a damp buff will distribute compound unevenly and may harbour contamination.