A cabochon dop — also called a cab dop — is a specialised dop stick whose working end is flat or very slightly concave, designed to hold a stone preform securely while the lapidary grinds and polishes it into a cabochon. It is the most fundamental tool in cabochon work, and its correct selection and use directly determines the symmetry, dome profile, and surface quality of the finished stone.

Construction and Materials

Cabochon dops are manufactured in wood, aluminium, and brass, each material offering a different balance of cost, heat conductivity, and durability. Wooden dops — traditionally dowel rod, often hardwood — are inexpensive and easy to shape, but they absorb moisture and can warp slightly over time. Aluminium dops are lightweight and conduct heat away from the adhesive bond more efficiently than wood, reducing the risk of the stone loosening during prolonged grinding. Brass dops are heavier and more dimensionally stable, making them a preferred choice among professional cutters who work with expensive rough where a dropped stone would be costly.

The flat or gently concave working face is the defining feature that distinguishes a cabochon dop from a faceting dop, whose end is precision-machined to a specific included angle. The flat face accommodates the irregular, often lumpy surface of a sawn preform, maximising the contact area available to the adhesive.

Sizing

Cabochon dops are produced in a graduated range of diameters, typically from approximately 6 mm up to 25 mm or larger, in increments of roughly 3–4 mm. The cutter selects a dop whose diameter is close to — but does not exceed — the planned girdle diameter of the finished stone. Using an undersized dop risks the adhesive bond failing under lateral grinding pressure; using an oversized dop can obstruct the cutter's view of the stone's outline and impede access to the girdle edge.

Adhesives: Dopping Wax and Epoxy

Two adhesive systems are in common use. Traditional dopping wax — a shellac-based thermoplastic compound — is melted over an alcohol lamp or dopping wax heater and applied between the preform and the dop face. The wax sets quickly and, crucially, releases cleanly when reheated, allowing the stone to be transferred to a second dop for working the reverse side without solvent or mechanical stress. Epoxy adhesives offer a stronger bond and are favoured for very small stones or for materials prone to cleaving under vibration, but they require chemical release agents or careful heat application to remove the finished stone without damage.

Proper dopping technique requires the preform to be warmed before wax application so that the wax does not chill and set before full contact is achieved. Air pockets trapped beneath the preform weaken the bond and can cause the stone to shift or detach mid-grind.

Role in the Cutting Sequence

In standard cabochon practice, the preform is first dopped with its table face — the flat, sawn base — against the dop face. The lapidary then works the dome on grinding wheels of progressively finer grit before moving to polishing laps. Once the dome is complete, the stone is transferred: a second dop is aligned coaxially with the first using a dop transfer jig, wax bridges the two dops, and after the wax sets the original dop is released by heat. The cutter then grinds and polishes the girdle and base. The cabochon dop's flat face is equally suited to both stages of this transfer sequence.

In the Trade

Cabochon dops are consumable workshop supplies rather than precision instruments, and they are sold individually or in assorted sets by lapidary suppliers worldwide. A cutter working commercially will maintain a full range of sizes and a supply of pre-shaped wax cones or sticks. The dop itself is rarely discussed in gem grading or trade contexts — its influence is entirely upstream of the finished stone — but its correct use is considered a baseline competency in any formal lapidary training programme.